This work was funded jointly by British Council (UK) and the Indi

This work was funded jointly by British Council (UK) and the Indian Government under the UK-India Education and research initiative (UK-IERI) postgraduate funding scheme. “
“Citation Mason KL, Aronoff DM. Postpartum group A Streptococcus sepsis and maternal immunology. https://www.selleckchem.com/products/cx-5461.html Am J Reprod Immunol 2012; 67: 91–100 Group A Streptococcus (GAS) is an historically important agent of puerperal infections and sepsis. The inception of hand-washing and improved hospital

hygiene drastically reduced the incidence of puerperal sepsis, but recently the incidence and severity of postpartum GAS infections has been rising for uncertain reasons. Several epidemiological, host, and microbial factors contribute to the risk for GAS infection and mortality in postpartum women. These include the mode of delivery (vaginal versus cesarean section), the location where labor and delivery occurred, exposure to GAS carriers, the altered immune status associated with pregnancy, the genetic background of the host, the virulence of the infecting GAS strain, and highly specialized immune responses associated with female reproductive tract tissues

and organs. This review will discuss the RAD001 chemical structure complicated factors that contribute to the increased susceptibility to GAS after delivery and potential reasons for the recent increase observed in morbidity and mortality. “
“Mesenchymal stem cells (MSCs) inhibit T-cell activation and proliferation but their effects on individual T-cell-effector pathways and on memory versus naïve T cells remain unclear. MSC influence

on the differentiation of naïve and memory CD4+ T cells toward the Th17 phenotype was examined. CD4+ T cells exposed to Th17-skewing conditions exhibited reduced CD25 and IL-17A expression following SPTLC1 MSC co-culture. Inhibition of IL-17A production persisted upon re-stimulation in the absence of MSCs. These effects were attenuated when cell–cell contact was prevented. Th17 cultures from highly purified naïve- and memory-phenotype responders were similarly inhibited. Th17 inhibition by MSCs was reversed by indomethacin and a selective COX-2 inhibitor. Media from MSC/Th17 co-cultures contained increased prostaglandin E2 (PGE2) levels and potently suppressed Th17 differentiation in fresh cultures. MSC-mediated Th17 inhibition was reversed by a selective EP4 antagonist and was mimicked by synthetic PGE2 and a selective EP4 agonist. Activation-induced IL-17A secretion by naturally occurring, effector-memory Th17 cells from a urinary obstruction model was also inhibited by MSC co-culture in a COX-dependent manner. Overall, MSCs potently inhibit Th17 differentiation from naïve and memory T-cell precursors and inhibit naturally-occurring Th17 cells derived from a site of inflammation. Suppression entails cell-contact-dependent COX-2 induction resulting in direct Th17 inhibition by PGE2 via EP4.

Under these circumstances it is highly likely that presentation o

Under these circumstances it is highly likely that presentation of autoantigen also takes place in the joint. Therefore, it could be speculated that, in RA, tolDC would ideally have the ability to act in several locations: in the rheumatoid joint to anergize autoantigen-specific effector T cells locally, and in the draining lymph node to

induce Tregs from autoantigen-specific naive T cells. However, it should be noted that T cells from RA patients can be resistant to at least some tolerogenic signals; for instance, they can resist Selleck RG7204 IL-10- and IDO-mediated suppression [90, 91]. Our tolDC operate, at least partially, via a TGF-β-dependent mechanism and inhibit proliferation and IFN-γ production of peripheral blood RA T cells in vitro (unpublished data); however, whether they can inhibit autoreactive T cells in the rheumatoid joint remains to be determined. Despite the fact that our tolDC have similar ability as mature DC to process and present exogenous antigen, tolDC have lower T cell stimulatory capacity than mature DC, in line with their lower expression of co-stimulatory molecules and low production of proinflammatory cytokines [55, 82]. Moreover, tolDC induce hyporesponsiveness (‘anergy’) in antigen-experienced memory T cells while

polarizing naive T cells towards an anti-inflammatory cytokine profile [55]. We have also shown that, in a mouse in-vivo model Forskolin datasheet of collagen-induced arthritis, murine bone marrow-derived tolDC generated with Dex, VitD3 and LPS have a therapeutic effect: treatment see more of arthritic mice with tolDC (1 million cells injected intravenously three times over 8 days) reduced significantly the severity and progression of arthritis, whereas treatment with immunogenic mature DC did not reduce disease and, in fact, exacerbated arthritis [49]. Interestingly, tolDC exerted a therapeutic effect only if they had been loaded with the immunizing antigen, type

II collagen. Treatment with tolDC was associated with a reduction in Th17 cells and an enhancement of IL-10-producing T cells, and a reduction in type II collagen-specific T cell proliferation, possibly explaining their therapeutic effect. Thus, this type of tolDC is a potentially powerful tool for the treatment of RA and other autoimmune diseases. Before tolDC can be applied in a clinical trial, a protocol to generate clinical grade tolDC, compliant with current good manufacturing practice (cGMP) regulations, had to be established. For this purpose, the research-grade fetal calf serum (FCS)-containing medium was replaced with cGMP-grade medium specialized for DC (CellGro® DC medium from CellGenix, Freiburg, Germany) and LPS was replaced with MPLA, a synthetic cGMP-grade TLR-4 ligand (from Avanti Polar Lipids, Alabaster, AL, USA).

In order to control for the effect of infection on the T cell sub

In order to control for the effect of infection on the T cell subpopulations, disease controls were recruited from the immunodeficiency clinic. These were immune-competent patients who had an increased infection burden, in whom no clinical or laboratory evidence for immunodeficiency was found. Results from this group were included only once a period of 1 year had elapsed since discharge from the clinic, to rule out an evolving immunodeficiency.

The immune tests undertaken were guided by clinical and family histories. The typical panel of tests performed included: IgG, IgA and IgM, and serum and urine electrophoresis with immunofixation if indicated. Specific antibody responses to the vaccines tetanus, pneumococcal and Haemophilius influenza B were performed, and if absent/low responses were noted the patient XL765 mouse was vaccinated and these retested after 1 month. Lymphocyte subsets, both percentage and absolute count, GDC-0068 research buy were also performed, including measurement of B cells, CD4 and CD8 T cells and natural killer (NK) cells [3,27]. At the time of analysis, all XLA and 55 of 58 CVID patients were on immunoglobulin

replacement, but not on immunosuppressive therapy. Those with autoimmune cytopenia or lymphoid interstitial pneumonia had not received corticosteroid therapy within 6 months, and only at prior doses <25 mg/kg. No patient had an affected parent, sibling or child. CVID patients

were categorized into the following clinical phenotypes, as described in Chapel et al. [2,3]: infection only (IO), enteropathy, lymphoid malignancy, polyclonal lymphoproliferation (PL), organ-specific autoimmune disease (OSAI) or autoimmune cytopenias (AC) which included immune thrombocytopenia (ITP). ITP is defined as platelets <100 × 109/l, persistent L-NAME HCl (>6 months), one episode treated with steroids [3]. The autoimmune diseases in patients in the OSAI group included: autoimmune thyroid disease (n = 5), psoriasis (n = 6), uveitis (n = 2), vitiligo (n = 2), pernicious anaemia (n = 3), ulcerative colitis (n = 4) and type 1 diabetes (n = 2). Only one patient had a subsequent lymphoid malignancy and only three had an enteropathy, so these categories were not utilized in the analysis; these patients were included in the CVID total group. Figure 1 demonstrates the distribution of clinical phenotypes of the CVID patient group. The number of patients stated in each group in Table 1 is the maximum number of patients analysed for a T cell subpopulation. However, for some of the T cell subpopulations smaller numbers were analysed due to either technical difficulties with a particular tube or limited sample availability. All flow cytometric analysis was performed on ethylenediamine tetraacetic acid (EDTA) blood samples within 48 h of venepuncture.

2), and n = 3 (exp 3) mice per group For day 60 p i , cytokine

2), and n = 3 (exp. 3) mice per group. For day 60 p.i., cytokine production and parasite burden in

IL-10FL/FL Cre− and IL-10FL/FL CD4-Cre+ were compared in two independent experiments using n = 3 (exp. 1) and n = 6 (exp. 2) mice per group and IL-10FL/FL Cre− and IL-10FL/FL CD19-Cre+ were compared in two independent experiments using n = 5 (exp. 1) and n = 5 (exp. 2) mice per group. Spleen cells were prepared from naive and infected mice at indicated time points after infection. A total of 5 × 105 spleen cells were cultivated in 96-well round bottom plates for 72 h at 37°C and 5% CO2 in RPMI 1640 medium supplemented with 10% FCS, l-glutamine (2 mg/mL), and gentamycin (50μg/mL). For stimulation, cells were either incubated with medium, 1 μg/mL anti-CD3 (145–2C11) or 12.5 μg/mL L. sigmodontis Ag (LsAg) (prepared as described [20]) in quadruplicates. Supernatants were collected Selleckchem Regorafenib and Vorinostat mw stored at -20°C until analysis. Cytokine concentrations in culture supernatants from spleen cells were quantified by ELISA (R&D Systems, Wiesbaden, Germany) according

to the manufacturer’s instructions. To measure proliferation cell cultures were labeled with 3H thymidine (0.25 μCi/well) and cultured for additional 18–20 h. Plates were frozen until detection of 3H thymidine uptake. The Fc receptors of spleen cells were blocked with Cohn II (Sigma Aldrich) for 10 min on ice. For surface staining, cells were stained with 1:100 dilutions of anti-CD3e-allophycocyanin (clone 145–2C11) and anti-CD49b-PE (clone DX5), with 1:250 dilutions of anti-CD4-allophycocyanin (clone GK1.5), anti-CD4-FITC (clone RM4.5), anti-CD8a-allophycocyanin (clone 53–6.7), anti-CD8a-PerCP cyanine-5.5 (PerCP Cy5.5) (clone 53–6.7), anti-CD11b-allophycocyanin (clone M1/70), anti-CD11c-allophycocyanin (clone N418), and anti-CD19-allophycocyanin (clone 1D3) or with 1:500 dilutions of anti-Gr-1-Alexa Etoposide Fluor 488 (clone RB6–8C5) and CD11b-PerCP Cy5.5 (clone M1/70) purchased from BioLegend (Aachen, Germany), BD Biosciences (Heidelberg, Germany), or eBioscience (San Diego, CA) as indicated for 30 min on ice. Foxp3 expression was determined using

PE–anti-mouse Foxp3 Staining Set (eBioscience) according to the manufacturer’s instructions. Samples were analyzed on a FACSCalibur Flow Cytometer (Becton Dickinson, Mountain View, CA) using Cell Quest software. All statistical tests were performed by ANOVA with Bonferroni posttest using Prism software (GraphPad Software, San Diego, CA). p values below 0.05 were considered statistically significant. I.H. is funded by the Werner-Otto-Stiftung. A.H. and S.S. are funded by the Deutsche Forschungsgemeinschaft SFB 704. We thank Matthias Haury and Dinis Calado for providing the IL-10-eGFP reporter mouse strain. The authors declare no financial or commercial conflict of interest. As a service to our authors and readers, this journal provides supporting information supplied by the authors.

The electrophoretic mobility shift assay was performed as describ

The electrophoretic mobility shift assay was performed as described previously [5]. The consensus sequence-specific oligo-nucleotide probes were end-labeled with γ-32P-ATP

according to the manufacturer’s recommendations. The oligonucleotide with the C/EBP consensus binding sequence used were 5′-GGTTCTTGCGCAACTCACTGAA-3′ and 3′-TTCAGTGAGTTGCGCAAGAACC-5 For SRT1720 purchase the binding reaction, 2 ng labeled oligonucleotide (approximately 20 000 cpm) and 2 μg poly dIdC (Amersham Pharmacia Biotech) carrier were incubated with 2 μg nuclear protein in a binding buffer (10 mM HEPES, 60 mM KCl, 1 mM DTT, 1 mM EDTA, 7% glycerol, and pH 7.6) for 30 min at room temperature. DNA–protein complexes were resolved on 6% nondenaturing polyacrylamide gels and visualized by exposure to autoradiographic films. Sprague-Dawley rats (230–250

g) were anesthetized by i.p. injection of chloral hydrate (400 mg/kg), positioned in a stereotaxic apparatus, and either LPS (from Salmonella enteritidis; Sigma, St. Louis, MO), IL-13, IL-13 antibody, or a combination of 2–3 were stereotactically injected into the right cerebral cortex (AP+4.8 mm ML, −5.5 mm, DV −6.0 mm from the bregma) according to Paxinos’ atlas. selleck chemicals llc The animals were categorized into to five groups: group I, PBS injection (30 μL); group II, LPS injection (10 μg); group III, IL-13 (100 μg) injection; group IV, LPS (10 μg) + IL-13 (100 μg) injection; and group V, LPS (10 μg) + IL-13 (100 μg) + IL-13 neutralized antibody (NA, 10 ng) in a final volume of 30 μL PBS injected at a rate of 0.15

μL/min using a 26-gauge Hamilton syringe attached to an automated pump Grape seed extract and left in situ for an additional 5 min to avoid reflux along the injection tract. A 1.5 m diameter, 45 cm deep Morris water maze was filled with water to a depth of 26.5 cm. The water temperature was kept at 26 ± 2˚C. A circular platform, 25 cm high, and 12 cm in diameter was placed into the tank at a fixed location in the centre of one of four imaginary quadrants. Approximately 1.5 L of milk was used to make the water opaque. The rat was then guided to swim to the platform. Activity in the water maze was recorded using a CCD camera on the ceiling above the centre of pool, which was attached to an automated tracking system (Noldus, Netherlands). A single experiment was performed with three rats. Behavioral measures included latency to targets, swing speed (cm/s), number of platform crosses, and percent time within the targeted area. Percent time in appositive object in reversal trial and in targeted object in extinction test was also conducted. Data were analyzed by Etho Vision 3.1. The animals were transcardially perfused with a saline solution containing 0.5% sodium nitrate and heparin (10 U/mL), followed by 4% paraformaldehyde dissolved in 0.1 M phosphate buffer (PB).

43 On the basis of survey and anecdotal information, the group co

43 On the basis of survey and anecdotal information, the group considered that the vast majority of laboratory reports in Australia and

New Zealand comply with this recommendation.48 Some key aspects of the recommendations from the Australasian Creatinine Consensus Working Group are summarized below: Pathology Obeticholic Acid datasheet laboratories should automatically report eGFR calculated using the ‘175’ MDRD formula, with every request for serum creatinine. Measurement of serum cystatin C can be also used to estimate GFR. This may be more accurate than creatinine based eGFR methods particularly at normal levels (90–120 mL/min) or above normal levels (>120 mL/min) but the assay is more expensive and is not yet generally available. Serial measurements of cystatin C levels have been shown to estimate progressive decline of GFR more accurately than creatinine based methods in both type 1 and type 2 diabetes. As with serum creatinine, the cystatin C is affected by factors other than the GFR and as with creatinine, knowledge of

these factors is required in both estimating the GFR and in the interpretation of eGFR in particular populations. Currently the non GFR factors associated with cystatin C are poorly defined which limits the routine application of serum cystatin C in the estimation of GFR both in people with and without type 2 diabetes.49–51 The recent review by Stevens et al.51 indicated Caspase inhibitor clinical trial many factors other than GFR to be associated with serum cystatin-C, including diabetes, measures of body size, higher C-reactive protein, higher white blood cell and lower serum albumin. The impact of these non GFR factors on serum cystatin C appear to be less than the non GFR influences

on serum creatinine, however, they remain poorly defined and may introduce significant variability within select sub populations. The recent study by Tidman 200852 concluded that the use of cystatin C only as ‘a determinator of eGFR does not yield improved accuracy’ over estimation using the MDRD formula alone, however, a formula that combines both serum most creatinine and cystatin C may provide greater accuracy, consistent with the conclusions made by.51 Databases searched: The search strategies were designed to reduce bias and ensure that most of the relevant data available on type 2 diabetes were included in the present review and were similar to those detailed in the Cochrane Collaboration Reviews Handbook (Higgins JPT et al.). The electronic databases searched were Medline, EMBASE, Cochrane Library, CINAHL, HTA and DARE. The detailed search strategy, research terms and yields are provided in Appendix 3 of the complete guideline document that can be found on the CARI website (http://www.cari.org.au). Date of searches: 28 March 2008.

In all patients, a free TMG flap was performed to reconstruct the

In all patients, a free TMG flap was performed to reconstruct the anterior axillary fold and the soft tissue defect. There

was no flap loss, and all three patients had a clearly improved appearance of the chest wall. In this article, we demonstrate our experience with the use of a TMG flap for chest wall reconstruction in male patients with Poland’s syndrome. © 2013 Wiley Periodicals, Inc. Microsurgery, 2013. “
“The purpose of this study was to compare the initial conditions and treatment outcomes of patients with advanced stage IV oral squamous cell carcinoma (OSCC) treated with or without free flap reconstruction FK228 clinical trial following ablative tumor resection. Two hundred forty-two pathological stage IV OSCC patients (without distant metastasis) treated by tumor ablation with free flap reconstruction (Group 1; n = 93) or without free flap reconstruction (Group 2; n = 149 treated with Proteasome inhibitor split-thickness skin grafts, primary closure of defects, secondary granulation of defects, and local or regional flaps) were recruited. We compared patient survival and cancer recurrence rates between these two groups. Group 1 had significantly more advanced tumor stage than group 2. Despite the unfavorably expected prognosis in group 1, both positive margin rate (17.2% in Group 1 versus 23.5% in Group 2, P = 0.213) and cancer recurrence rate (36.6% in Group

1 versus 38.3% in Group 2; P = 0.792) were not significantly different between the two groups. The 5-year disease-specific survival were also the same (51.4% in Group 1 versus 52.6% in Group 2; P = 0.493). Although cancer stages were more advanced

in patients requiring free flap reconstruction, patient survival, and cancer recurrence in the patients with free flap reconstruction were maintained as patients without free flap. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012. “
“Distally based sural fasciocutaneous flap is traditionally raised by the Amylase retrograde method. This article introduces the anterograde–retrograde method for harvest of the flap and describes our experience on altering the flap plan. A total of 159 flaps in 154 patients were elevated by the anterograde–retrograde approach that harvest of the flap began with exploring the peroneal artery perforators nearby the pivot point before the upper and bilateral edges of the flap were incised. Partial necrosis occurred in 16 (10.1%) flaps, and marginal necrosis developed in 10 flaps. Nine flaps were redesigned with adjusted pivot point and skin island. The anterograde–retrograde approach for harvest of the flap can accurately locate the perforator, readily adjust both the pivot point and skin island if necessary, and thus improve reliability of the flap. This approach is particularly applicable for elevation of the flap without preoperative localization of the perforators by means of the Doppler. © 2012 Wiley Periodicals, Inc.

[59] Dasatinib, a Src kinase inhibitor and a preclinical drug for

[59] Dasatinib, a Src kinase inhibitor and a preclinical drug for chronic-phase chronic myeloid leukaemia,[60] is also on the study list. As reported, learn more dasatinib could reduce MMP9+ macrophage density and inhibit MMP9 expression in the tumour microenvironment.[61] This observation broadened the therapeutic mechanisms of dasatinib. To deplete TAMs by targeting their surface molecules with immunotoxin-conjugated agents is another approach for tumour therapy. Such studies have been conducted for ovarian cancer treatment by using immunotoxin-conjugated mAbs, where the surface proteins of TAMs, such as scavenger

receptor-A and CD52, were targeted.[62, 63] Folate receptor β (FRβ) is another surface protein worth targeting because it is over-expressed in M2-like TAMs,[64, 65] and the existence of FRβ+ macrophages positively associates with high vessel density, high incidence of haematogenous metastasis and a poor prognosis in patients with pancreatic cancer.[66] Nagai et al.[64] reported the inhibitory effects of the folate–immunotoxin conjugate on tumour growth, accomplished with the depletion of TAMs. One benefit of this approach may be that while pro-tumoral M2 TAMs could be depleted, the M1 tumoricidal ones are not affected. Recent studies demonstrate that several bacteria prefer to take macrophages as targets. For instance, it was reported Selleckchem Sirolimus that

Shigella flexneri infection could selectively induce the apoptosis of macrophages,[67] and a single injection of an attenuated strain of Shigella flexneri to tumour-bearing mice resulted in the apoptosis of TAMs, followed by a 74% reduction in size of tumours.[68] In addition, other bacteria, such as Salmonella typhimurium, Listeria monocytogens, Chlamydia psittaci and Legionella pneumophila, are

also considered to be useful for TAM-targeted immunotherapy because they harbour primarily in macrophages.[21] Other than directly inducing the apoptosis of TAMs as mentioned above, another available approach for TAM suppression is to evoke acquired immune responses, in which cytotoxic T lymphocytes act as the scavengers of TAMs because they can naturally target the membrane molecules of macrophages. Thalidomide In other words, up-regulating the membrane molecules that could be recognized by T cells in TAMs would be a potential method of TAM depletion. One such molecule is legumain, a lysosomal protease highly expressed in many human tumours; which promotes neoplastic cell invasion and metastasis.[69] Luo et al.[24] originally found that legumain is over-expressed in M2-like TAMs. In the following studies, they immunized tumour-bearing mice with a novel legumain-based DNA vaccine, and found that this vaccine activated dendritic cells, which then triggered multi-step reactions including the antigen presenting, co-stimulation of cytotoxic CD8+ T cells and the specific abrogation of legumain-expressing TAMs.

As will be discussed here, reproductive immunology is a very good

As will be discussed here, reproductive immunology is a very good example of how paradigms have shaped our understanding of immune regulation but don’t provide all of the answers. A central paradigm of modern

immunology is the clonal-selection theory, formulated by F. MacFarlane Burnet1 in the late 1950s, which explains how immune system makes antibody responses to diverse antigens and IWR-1 nmr discriminates self from non-self. The key features of the clonal-selection theory are that (i) each lymphocyte bears antigenic receptors of a single specificity; (ii) receptor specificity and diversity is germline-encoded, randomly generated and precedes antigen encounter; (iii) lymphocytes with receptors that recognize self-molecules are deleted at an early stage of development; and (iv) antigen encounter of mature lymphocytes leads to clonal expansion and consequently adaptive immunological memory. The clonal-selection theory has prompted

much debate and been Hydroxychloroquine supplier challenged as being over-simplified in its view of self–non-self discrimination by (among others) Polly Matzinger’s Danger model and Charles Janeway’s pathogenicity model.2 However, it is worth noting that Burnet made his discovery in an era prior to the development of all the transgenic and knock-out mice, molecular probes and monoclonal antibodies (moAbs) that now permit a more detailed dissection of the immune system and test the predictions of paradigms more fully. MacFarlane Burnet’s work was groundbreaking, and he shared the 1960 Nobel Prize for Medicine or Physiology with Peter Medawar for the discovery of immunological tolerance (http://nobelprize.org/nobel_prizes/medicine/laureates/). However, Peter Medawar was also among the first to recognize that a simple self–non-self model was not absolute in its predictions of immunological tolerance and immune activation, as it could not explain the phenomenon of mammalian

pregnancy Histamine H2 receptor in the face of a functional maternal immune system. Medawar3 formulated three hypotheses that could help explain placentation and mammalian reproduction within the context of self–non-self discrimination. These hypotheses formed the basis of three new paradigms of reproductive immunology, namely that (i) the maternal immune system is suppressed; (ii) the placenta acts a barrier between the mother and foetus; and (iii) the foetus is antigenically immature and therefore not recognized by the maternal immune system. The status of these paradigms was eloquently reviewed by David Billington4 in 2003 to mark the 50th anniversary of Medawar’s publication. With better immunological tools, we now know that Medawar’s paradigms were over-simplified, with the exception of the importance of anatomical separation of the mother and foetus by the placenta. However, like other important paradigms, they fuelled key discoveries in reproductive immunology and in turn have led to the formulation of modified and new paradigms.

Higher-quality studies consistently find significant bivariate as

Higher-quality studies consistently find significant bivariate associations between early sexual debut and HIV. In some studies, the increase in women’s HIV infection risk seems to result from women’s later engagement in risky sexual behaviours, rather than being

directly related to early onset of sexual debut. In other studies, the increase in risk did not seem to be due to specific behavioural risk characteristics of the respondents or their sexual partners, BI 6727 suggesting that the risk may relate more to the potential for biological factors, for example, genital trauma, or other factors that have not been captured by the studies in this review. In many sub-Saharan African countries, there are disturbingly high levels of HIV infection among young women – with the discrepancies in ratios of HIV infection between 16- and 24-year-old girls compared with boys being eightfold higher in some settings.[1] Girls’ HIV vulnerability

is underpinned by a range of social norms and gender inequalities that often lead to adolescent girls commencing sex at an earlier age than adolescent boys. Young age at first sexual debut has long been discussed as a potentially important risk factor for HIV infection among women. Indeed, in Uganda in the 1990s, the rapid increase in age at first sex in urban areas was considered to be an important contributing click here factor in the decline of HIV prevalence.[2] For such reasons, initiatives to delay sexual debut have been considered as a potentially important

component of HIV prevention programmes in sub-Saharan Africa.[3] However, although girls’ early sexual debut has been posited as an important risk factor for HIV infection, the mechanisms through which this increased risk may occur these have not been fully explored. Early sexual debut could potentially increase women’s risk of HIV infection in four different ways. Firstly, early sexual debut may increase women’s HIV infection risk due to the extended duration of sexual activity, because women who started sex early have a longer duration of sexual activity, and they are therefore potentially exposed to HIV infection risk for a longer period of time.[4, 5] Although this explanation in reality is likely to be collinear with women’s age at first sex, most studies using cross-sectional survey data recruit women of different ages and therefore have different periods of exposure to sexual activity at the time of measurement irrespective of women’s age at first sex.[4, 5] Second, it may be that women who commence sex early may also be more prone to engage in risky sexual behaviours later on, such as having a high number of sexual partners, including premarital, casual partners or sex partners through transactional sex, a greater age disparity with the partner, lower rates of contraceptive and condom use, sexually transmitted infection (STI) and pelvic inflammatory diseases.