Activating NK‐cell receptors co‐stimulate CD4+CD28− T cells in patients with rheumatoid arthritis

Effector T‐cell responses can be modulated by competing positive or negative signals transduced by NK‐cell receptors (NKR). In the CD4⁺ T‐cell population, the expression of NKR is primarily found in the CD4⁺CD28⁻ T‐cell subset, also known as CD28^null T cells. These T cells are frequently found in rheumatoid arthritis (RA) and other inflammatory disorders, suggesting that signaling through NKR may play a role in the autoimmune reaction. Here we aimed to dissect the phenotype and function of NKR‐expressing CD4⁺CD28⁻ T cells in patients with RA. By analyzing a broad array of NKR on CD4⁺CD28⁻ T cells we found a significant expression of the co‐activating receptors 2B4 (CD244), DNAM‐1 (CD226), and CRACC. Pair‐wise ligations of 2B4 with DNAM‐1 and/or NKG2D lead to increased effector functions of primary CD4⁺CD28⁻ T cells to suboptimal levels of anti‐CD3 stimulation. Using multi‐parameter flow cytometry, we demonstrate that such co‐ligation led to an increased magnitude in overall responsiveness without changing qualitative aspects of the response. Altogether these results demonstrate a pattern of additive effects in NKR‐mediated functional modulation of CD4⁺CD28⁻ T cells in RA. This may have consequences for the inflammatory responses imposed by these cells, thus influencing disease manifestations.     

SHORT COMMUNICATION: CD3− CD56+ CD16+ Natural Killer Cells and Improvement of Pregnancy Outcome in IVF/ICSI Failure After Additional IVIG‐Treatment

Citation Heilmann L, Schorsch M, Hahn T. CD3^? CD56⁺ CD16⁺ Natural killer cells and improvement of pregnancy outcome in IVF/ICSI failure after additional IVIG‐treatment. Am J Reprod Immunol 2010; 63: 263–265 Problem The purpose of this retrospective, observational study was to investigate whether additional treatment with intravenous immunglobulin (IVIG) increased the rate of successful pregnancies after repeated implantation failure (RIF). The retrospective data were compared with data of patients without IVIG‐therapy from the meta‐analysis of Clark et al. Method of study A total of 188 women with 226 treatment cycles between 2007 and 2009 were evaluated for IVIG therapy. The percentage of NK cells was measured two times before a new embryo transfer (only women with NK cell percentages >12% were included) and after embryo transfer at a positive pregnancy test. Results In comparison with the meta‐analysis of Clark et al., we observed a pregnancy rate of 50.5%, an implantation rate of 21% and a miscarriage rate of 16.8%. In 42%/IVIG‐ patient or 34.9%/embryo transfer, we observed a live born baby. The live born rate per embryo was 16.6%. In accordance with the study of Kwak et al., we indicate a decrease in the NK cells in patients with improved pregnancy outcome. Conclusion In a subgroup of RIF‐patients with high level of CD56⁺ CD16⁺ NK‐cells the additional application of IVIG leads to a favourable pregnancy outcome.     

Murine CXCR3+CD27bright NK cells resemble the human CD56bright NK‐cell population

Human NK cells can be subdivided into CD56^dim and CD56^bright NK cells, which exhibit different phenotypical and functional characteristics. As murine NK cells lack CD56 or a distinct correlate, direct comparative studies of NK cells in mice and humans are limited. Although CD27 is currently proposed as a feasible subset marker in mice, we assume that the usage of this marker alone is insufficient. We rather investigated the expression of the chemokine receptor CXCR3 for its suitability for distinguishing murine NK‐cell subsets with simultaneous consideration of CD27. Compared with CXCR3^? NK cells, exerting stronger cytotoxic capability, CXCR3⁺ NK cells displayed an activated phenotype with a lower expression of Ly49 receptors, corresponding to human CD56^bright NK cells. Also in common with human CD56^bright NK cells, murine CXCR3⁺ NK cells exhibit prolific expansion as well as robust IFN‐γ, TNF‐α and MIP‐1α production. We additionally demonstrated changes in both CXCR3 and CD27 expression upon NK‐cell activation. In summary, CXCR3 serves as an additional applicable marker for improved discrimination of functionally distinct murine NK‐cell subsets that comply with those in humans.     

A population of CD62Llow NK1.1− CD4+ T cells that resembles NK1.1+ CD4+ T cells

In MHC class II−/− C57BL/6 (II−/−) mouse spleen, a small population of CD4⁺ T cells is present of which NK1.1⁺ CD4⁺ (NK) T cells comprise 40 to 45 %. We report here that many of the NK1.1⁻ CD4⁺ T cells derived from II−/− mice are also NK T cells. They produce large amounts of IL-4 in response to anti-CD3 ligation and do so without any requirement for the presence of IL-4 in the priming culture, a property characteristic of NK T cells. Their IFN-γ production is large and is enhanced by IL-12. In addition, II−/− NK1.1⁻ CD4⁺ T cells produce IL-4 as a result of culture with L cells expressing murine CD1 (L-CD1). We report that CD49b, a component of integrin VLA-2, is expressed on the majority of both NK1.1⁺ and NK1.1⁻ NK T cells. NK1.1⁻ NK T cells also exist in wild-type C57BL/6 mice. Evidence supporting this is that Vβ8 usage by CD62L^low NK1.1⁻ CD4⁺ T cells was ∼ 5 % higher than that by CD62L^high CD4⁺ T cells in wild-type mice in keeping with the estimated proportion of NK1.1⁻ NK T cells in the CD62L^low population. CD62L^low CD4⁺ T cells from β2-m−/− mice, which lack NK T cells, showed no increase in Vβ8 usage. When activated by anti-CD3 or L-CD1, CD62L^low NK1.1⁻ CD4⁺ T cells from conventional but not β2-m−/− and CD1−/− mice produce IL-4 in a manner indistinguishable from II−/− NK1.1⁻ CD4⁺ T cells. NK1.1⁻ NK T cells in normal mouse spleens are approximately as numerous as NK1.1⁺ NK T cells.     

H2‐M3‐restricted CD8+ T cells augment CD4+ T‐cell responses by promoting DC maturation

Infection with Listeria monocytogenes triggers the activation and expansion of nonconventional CD8⁺ T cells restricted by the MHC class Ib molecule, H2‐M3. H2‐M3‐restricted CD8⁺ T cells exhibit a memory phenotype, rapidly produce cytokines, and reach peak frequencies sooner than conventional MHC class Ia‐restricted CD8⁺ T cells. In this study, we found that simultaneous in vivo priming of H2‐M3‐restricted T cells and adoptively transferred OT‐II CD4⁺ T cells on the same DC enhances the survival of OT‐II cells. Stimulation of H2‐M3‐restricted T cells were found to induce DC maturation resulting in costimulatory molecule upregulation and production of T_H1‐type cytokines, which was dependent on both cell‐to‐cell contact and soluble factors, particularly TNF‐α, produced by activated H2‐M3‐restricted T cells. Interestingly, H2‐M3‐restricted T cells were more efficient than activated NK cells in inducing DC maturation. Furthermore, we found that OVA_323–339‐coated DC matured by coculturing with peptide‐stimulated H2‐M3‐restricted T cells were more efficient in stimulating the proliferation of Ag‐activated OT‐II cells. This study indicates that H2‐M3‐restricted T cells promote immune responses by CD4⁺ T cells by inducing DC maturation and suggests novel mechanisms for vaccine development.     

Mesenteric lymph node CD11b− CD103+ PD‐L1High dendritic cells highly induce regulatory T cells

Dendritic cells (DCs) in mesenteric lymph nodes (MLNs) induce Foxp3⁺ regulatory T cells to regulate immune responses to beneficial or non‐harmful agents in the intestine, such as commensal bacteria and foods. Several studies in MLN DCs have revealed that the CD103⁺ DC subset highly induces regulatory T cells, and another study has reported that MLN DCs from programmed death ligand 1 (PD‐L1) ‐deficient mice could not induce regulatory T cells. Hence, the present study investigated the expression of these molecules on MLN CD11c⁺ cells. Four distinct subsets expressing CD103 and/or PD‐L1 were identified, namely CD11b⁺ CD103⁺ PD‐L1^High, CD11b⁻ CD103⁺ PD‐L1^High, CD11b⁻ CD103⁺ PD‐L1^Low and CD11b⁺ CD103⁻ PD‐L1^Int. Among them, the CD11b⁻ CD103⁺ PD‐L1^High DC subset highly induced Foxp3⁺ T cells. This subset expressed Aldh1a2 and Itgb8 genes, which are involved in retinoic acid metabolism and transforming growth factor‐β (TGF‐β) activation, respectively. Exogenous TGF‐β supplementation equalized the level of Foxp3⁺ T‐cell induction by the four subsets whereas retinoic acid did not, which suggests that high ability to activate TGF‐β is determinant for the high Foxp3⁺ T‐cell induction by CD11b⁻ CD103⁺ PD‐L1^High DC subset. Finally, this subset exhibited a migratory DC phenotype and could take up and present orally administered antigens. Collectively, the MLN CD11b⁻ CD103⁺ PD‐L1^High DC subset probably takes up luminal antigens in the intestine, migrates to MLNs, and highly induces regulatory T cells through TGF‐β activation.     

Human antigen‐specific CD4+CD25+CD134+CD39+ T cells are enriched for regulatory T cells and comprise a substantial proportion of recall responses

Human Ag‐specific CD4⁺ T cells can be detected by their dual expression of CD134 (OX40) and CD25 after a 44 hours stimulation with cognate Ag. We show that surface expression of CD39 on Ag‐specific cells consistently identifies a substantial population of CD4⁺CD25⁺CD134⁺CD39⁺ T cells that have a Treg‐cell‐like phenotype and mostly originate from bulk memory CD4⁺CD45RO⁺CD127^lowCD25^highCD39⁺ Treg cells. Viable, Ag‐specific CD25⁺CD134⁺CD39⁺ T cells could be expanded in vitro as cell lines and clones, and retained high Forkhead Box Protein 3, CTLA‐4 and CD39 expression, suppressive activity and Ag specificity. We also utilised this combination of cell surface markers to measure HIV‐Gag responses in HIV⁺ patients before and after anti‐retroviral therapy (ART). Interestingly, we found that the percentage of CD39^? cells within baseline CD4⁺ T‐cell responses to HIV‐Gag was negatively correlated with HIV viral load pre‐ART and positively correlated with CD4⁺ T‐cell recovery over 96 weeks of ART. Collectively, our data show that Ag‐specific CD4⁺CD25⁺CD134⁺CD39⁺ T cells are highly enriched for Treg cells, form a large component of recall responses and maintain a Treg‐cell‐like phenotype upon in vitro expansion. Identification and isolation of these cells enables the role of Treg cells in memory responses to be further defined and provides a development pathway for novel therapeutics.     

IL‐15‐dependent CD8+CD122+ T cells ameliorate experimental autoimmune encephalomyelitis by modulating IL‐17 production by CD4+ T cells

Interleukin‐15 (IL‐15) is an inflammatory cytokine whose role in autoimmune diseases has not been fully elucidated. Th17 cells have been shown to play critical roles in experimental autoimmune encephalomyelitis (EAE) models. In this study, we demonstrate that blockade of IL‐15 signaling by TMβ‐1 mAb treatment aggravated EAE severity. The key mechanism was not NK‐cell depletion but depletion of CD8⁺CD122⁺ T cells. Adoptive transfer of exogenous CD8⁺CD122⁺ T cells to TMβ‐1‐treated mice rescued animals from severe disease. Moreover, transfer of preactivated CD8⁺CD122⁺ T cells prevented EAE development and significantly reduced IL‐17 secretion. Naïve effector CD4⁺CD25^? T cells cultured with either CD8⁺CD122⁺ T cells from wild‐type mice or IL‐15 transgenic mice displayed lower frequencies of IL‐17A production with lower amounts of IL‐17 in the supernatants when compared with production by effector CD4⁺CD25^? T cells cultured alone. Addition of a neutralizing antibody to IL‐10 led to recovery of IL‐17A production in Th17 cultures. Furthermore, coculture of CD8⁺CD122⁺ T cells with effector CD4⁺ T cells inhibited their proliferation significantly, suggesting a regulatory function for IL‐15 dependent CD8⁺CD122⁺ T cells. Taken together, these observations suggest that IL‐15, acting through CD8⁺CD122⁺ T cells, has a negative regulatory role in reducing IL‐17 production and Th17‐mediated EAE inflammation.     

Therapeutic envelope vaccination in combination with antiretroviral therapy temporarily rescues SIV‐specific CD4+ T‐cell‐dependent natural killer cell effector responses in chronically infected rhesus macaques

Natural killer (NK) cells are essential components of the immune system, and due to their rapid response potential, can have a great impact during early anti‐viral immune responses. We have previously shown that interleukin‐2‐dependent NK and CD4⁺ T‐cell co‐operative immune responses exist in long‐term simian immunodeficiency virus (SIV) ‐infected controlling macaques and can be rescued in SIV‐infected non‐controlling macaques by a short course of antiretroviral therapy (ART). Given that co‐operative responses may play an important role in disease prevention and therapeutic treatment, in the present study we sought to determine if these responses can be enhanced in chronically SIV‐infected macaques by vaccination with a single‐dose of envelope protein given during ART. To this end, we treated 14 chronically SIV‐infected macaques with ART for 11 weeks and gave 10 of these macaques a single intramuscular dose of SIV gp120 at week 9 of treatment. ART significantly decreased plasma and mucosal viral loads, increased the numbers of circulating CD4⁺ T cells in all macaques, and increased T‐cell‐dependent envelope‐ and gag‐specific interferon‐γ and tumour necrosis factor‐α production by circulatory CD56⁺ NK cells. The therapeutic envelope immunization resulted in higher envelope‐specific responses compared with those in macaques that received ART only. Functional T‐cell responses restored by ART and therapeutic Env immunization were correlated with transiently reduced plasma viraemia levels following ART release. Collectively our results indicate that SIV‐specific T‐cell‐dependent NK cell responses can be efficiently rescued by ART in chronically SIV‐infected macaques and that therapeutic immunization may be beneficial in previously vaccinated individuals.     

Mycobacterium chelonae sensitisation induces CD4+‐mediated cytotoxicity against BCG

Significant variability in efficacy of live Mycobacterium bovis BCG as a tuberculosis vaccine is observed globally. Effects of pre‐vaccination sensitisation to non‐tuberculous environmental mycobacteria (Env) are suspected to underlie this phenomenon, but the mechanisms remain unclear. We postulated that it could be due to Env‐specific T cells exerting cytotoxicity against BCG‐infected host cells. After murine sensitisation with heat‐killed antigens of different Env species, splenocytes from M. chelonae (CHE)‐sensitised mice exerted the strongest cytotoxicity against autologous BCG‐infected macrophages. This cytotoxicity was correlated with reduced BCG viability. The cytotoxicity was reduced by the depletion of CD4⁺, but not CD8⁺ or CD56⁺ cells, and CD4⁺ cells showed higher percentage of cytotoxicity than CD4^? cells, supporting a role for CD4⁺ cells in CHE‐induced, BCG‐specific cytotoxicity. Additionally, this cytotoxicity was IFN‐γ, perforin and FasL dependent. After CHE‐sensitisation and subsequent BCG intranasal infection, there was significant expansion of lung CD4⁺ cells, the main cell type producing IFN‐γ. This was associated with 2‐ and 6‐fold reductions in lung BCG counts 1 and 3 wk, respectively post‐ infection, relative to non‐sensitised mice. This is the first report describing cytotoxicity against BCG‐infected cells as a mechanism underlying the influence of Env sensitisation on subsequent BCG responses.     

Expansion of CD56+ NK T and γδ T cells from cord blood of human neonates

A particular T cell population expressing NK cell markers, CD56 and CD57, exists in humans. Many CD56⁺ T and CD57⁺ T cells (i.e. NK T cells) exist in the liver and increase in number in the blood with ageing. They may be a human counterpart of extrathymic T cells, similar to NK1.1⁺ CD3^int cells seen in mice. We investigate here the existence of such NK T cells in human cord blood and the in vitro expansion of these cells by the stimulation of human recombinant IL-2 (rIL-2). There were very small populations (< 1.0%) of CD56⁺ T cells, CD57⁺ T cells, and γδ T cells in cord blood. However, all of these populations increased in number after birth and with ageing. When lymphocytes in cord blood were cultured with rIL-2 (100 U/ml) for 14 days, CD56⁺ T cells expanded up to 25% of T cells. CD57⁺ T cells were never expanded by these in vitro cultures. The expansion of γδ T cells (mainly Vγ9^? non-adult type) also occurred in the in vitro culture. A considerable proportion of CD56⁺ T cells was found to use Vα24 (i.e. equivalent to invariant Vα14 chain used by murine NK T cells) for TCR αβ. These results suggest that neonatal blood contains only a few NK T cells but CD56⁺ NK T cells and γδ T cells are able to expand in vitro.     

Recurrent superantigen exposure in vivo leads to highly suppressive CD4+CD25+ and CD4+CD25‐ T cells with anergic and suppressive genetic signatures

Staphylococcal enterotoxin B (SEB) activates T cells via non‐canonical signalling through the T cell receptor and is an established model for T cell unresponsiveness in vivo. In this study, we sought to characterize the suppressive qualities of SEB‐exposed CD4⁺ T cells and correlate this with genetic signatures of anergy and suppression. SEB‐exposed CD25⁺ and CD25^‐Vβ8⁺CD4⁺ T cells expressed forkhead box P3 (FoxP3) at levels comparable to naive CD25⁺ T regulatory cells and were enriched after exposure in vivo. Gene related to anergy in lymphocytes (GRAIL), an anergy‐related E3 ubiquitin ligase, was up‐regulated in the SEB‐exposed CD25⁺ and CD25^‐FoxP3⁺Vβ8⁺CD4⁺ T cells and FoxP3^‐CD25^‐Vβ8⁺CD4⁺ T cells, suggesting that GRAIL may be important for dominant and recessive tolerance. The SEB‐exposed FoxP3⁺GRAIL⁺ T cells were highly suppressive and non‐proliferative independent of CD25 expression level and via a glucocorticoid‐induced tumour necrosis factor R‐related protein‐independent mechanism, whereas naive T regulatory cells were non‐suppressive and partially proliferative with SEB activation in vitro. Lastly, adoptive transfer of conventional T cells revealed that induction of FoxP3⁺ regulatory cells is not operational in this model system. These data provide a novel paradigm for chronic non‐canonical T cell receptor engagement leading to highly suppressive FoxP3⁺GRAIL⁺CD4⁺ T cells.     

Steady‐state antigen‐expressing dendritic cells terminate CD4+ memory T‐cell responses

CD4⁺ T cells are important effectors of inflammation and tissue destruction in many diseases of immune dysregulation. As memory T cells develop early during the preclinical stages of autoimmune and inflammatory diseases, immunotherapeutic approaches to treatment of these diseases, once established, must include the means to terminate memory T‐cell responses. Traditionally, it has been considered that, due to their terminally differentiated nature, memory T cells are resistant to tolerance induction, although emerging evidence indicates that some immunotherapeutic approaches can terminate memory T‐cell responses. Here, we demonstrate that CD4⁺ memory T‐cell responses can be terminated when cognate antigen is transgenically expressed in steady‐state DC. Transfer of in‐vitro‐generated CD4⁺ memory T cells establishes, in nontransgenic recipients, a stable and readily recalled memory response to cognate antigen. In contrast, upon transfer to mice expressing cognate antigen targeted to DC, memory CD4⁺ T cells undergo a phase of limited proliferation followed by substantial deletion, and recall responses are effectively silenced. This finding is important in understanding how to effectively apply immunotherapy to ongoing T‐cell‐mediated autoimmune and inflammatory diseases.     

Control of Schistosoma mansoni egg‐induced inflammation by IL‐4‐responsive CD4+CD25−CD103+Foxp3− cells is IL‐10‐dependent

Host protection to helminth infection requires IL‐4 receptor α chain (IL‐4Rα) signalling and the establishment of finely regulated Th2 responses. In the current study, the role of IL‐4Rα‐responsive T cells in Schistosoma mansoni egg‐induced inflammation was investigated. Egg‐induced inflammation in IL‐4Rα‐responsive BALB/c mice was accompanied with Th2‐biased responses, whereas T‐cell‐specific IL‐4Rα‐deficient BALB/c mice (iLck^creIl4ra^?/lox) developed Th1‐biased responses with heightened inflammation. The proportion of Foxp3⁺ Treg in the draining LN of control mice did not correlate with the control of inflammation and was reduced in comparison to T‐cell‐specific IL‐4Rα‐deficient mice. This was due to IL‐4‐mediated inhibition of CD4⁺Foxp3⁺ Treg conversion, demonstrated in adoptively transferred Rag2^?/? mice. Interestingly, reduced footpad swelling in Il4ra^?/lox mice was associated with the induction of IL‐4 and IL‐10‐secreting CD4⁺CD25^?CD103⁺Foxp3^? cells, confirmed in S. mansoni infection studies. Transfer of IL‐4Rα‐responsive CD4⁺CD25^?CD103⁺ cells, but not CD4⁺CD25^high or CD4⁺CD25^?CD103^? cells, controlled inflammation in iLck^creIl4ra^?/lox mice. The control of inflammation depended on IL‐10, as transferred CD4⁺CD25^?CD103⁺ cells from IL‐10‐deficient mice were not able to effectively downregulate inflammation. Together, these results demonstrate that IL‐4 signalling in T cells inhibits Foxp3⁺ Treg in vivo and promotes CD4⁺CD25^?CD103⁺Foxp3^? cells that control S. mansoni egg‐induced inflammation via IL‐10.     

Epithelial expression of human papillomavirus type 16 E7 protein results in peripheral CD8 T‐cell suppression mediated by CD4+CD25+ T cells

The role of thymic versus peripheral epithelium in the regulation of the antigen‐specific CD8 T‐cell repertoire is still largely unresolved. We generated TCR‐β chain transgenic mice in which an increased frequency of peripheral CD8 T cells recognizes an epitope from a viral oncoprotein (HPV16E7) in the context of H‐2D^b MHC class I. When T cells from these mice developed through the thymus of mice expressing functional E7 protein from a keratin 14 promoter, no major perturbation to transgenic T‐cell development in the thymus was observed in these double‐transgenic mice. In contrast, peripheral CD8 T‐cell responses in the single‐transgenic, K14E7 mice, including those unrelated to E7 antigen, are reduced whereas CD4 T‐cell responses and antibody production are unchanged in these mice. Peripheral non‐responsiveness among CD8 T cells was mediated largely by CD4⁺CD25⁺ T cells. This suggested that epithelium expressing HPV16E7 protein induces Treg that specifically down‐regulate CD8 T‐cell responses in the periphery. This may have important consequences for the treatment of cervical pre‐cancers and provides a model for understanding differential suppression of T and B lymphocyte subsets by Treg.     

Adipocyte‐derived lipids modulate CD4+ T‐cell function

Adipose tissue contains several immune cells whose number and phenotype vary depending on the adiposity. In the present study, we show that IFN‐γ⁺ CD4⁺ T cells are enriched in human adipose tissue compared with in blood. To gain insight into the underlying mechanisms, we investigated the possibility that human adipocytes modulate CD4⁺ T‐cell cytokine production and proliferation and show that CD4⁺ T cells produced increased levels of IFN‐γ when activated in the presence of adipocytes. This effect was mediated by soluble mediators, as shown in transwell and adipocyte‐conditioned medium (ACM) transfer experiments. Additionally, ACM induced increased proliferation of CD4⁺ T cells upon activation. Intriguingly, the proliferation‐enhancing effect resided mainly in the lipid fraction of ACM, as shown upon separation of the protein and lipid fraction. Further separation of these lipids based on polarity revealed that the modulatory effect is confined to fractions containing free fatty acids. All identified fatty acids were able to individually enhance T‐cell proliferation. These data indicate that adipocytes can modulate CD4⁺ T‐cell function through the release of lipids. Remarkably, free fatty acids were the most prominent modulators of T‐cell proliferation, possibly leading to an accumulation of these cells in adipose tissue.     

Early increase of CD4+ CD45RA+ and CD4+ CD95− cells with conserved repertoire induced by anti-retroviral therapy in HIV-infected patients

Administration of anti-retroviral drugs induces a decrease of viral load associated with increase of CD4⁺ cell count in most HIV-infected patients. To investigate the early changes in CD4⁺ cell phenotype induced by anti-retroviral therapy, six patients with CD4⁺ cell count > 100/mm³ and never treated with anti-HIV therapy were enrolled and blood samples collected several times within 14 days from the initiation of therapy with Zidovudine plus Didanosine. CD4⁺ cell count and HIV viraemia were investigated at each time point, as well as the expression of CD45RA, CD45RO and CD95/Fas molecules on CD4⁺ cells, and the T cell receptor (TCR) Vβ repertoire of CD4⁺ cells. All patients showed a rapid and dramatic decrease in viral load with a corresponding increase of CD4⁺ cell count. The main remodelling of CD4⁺ cell subpopulations took place in the first 14 days of therapy, and consisted of: (i) increased CD4⁺ CD45RA⁺/CD4⁺ CD45RO⁺ ratio; (ii) decrease of CD95/Fas expression. The rise in absolute number of CD4⁺ CD45RA⁺ cells was paralleled by an increase of CD4⁺ CD95/Fas^? cells and accounted for most of the early increment of CD4⁺ cell count. The TCR Vβ repertoire of CD4⁺ cells was conserved after anti-HIV therapy, with the exception of two patients with expanded CD4⁺ Vβ12⁺ cells, which also tested CD45RA⁺ and CD95/Fas^?. These experiments show that newcomer CD4⁺ lymphocytes are CD45RA⁺ CD95/Fas^? cells, suggesting that blocking HIV replication causes an early and antigen-independent proliferation of possibly ‘naive’ cells unprimed for CD95/Fas-mediated apoptosis. These cells expressed a conserved and widespread TCR repertoire, suggesting that their capability for antigenic recognition is intact.     

The Distribution of CD56dimCD16+ and CD56brightCD16− Cells are Associated with Prolactin Levels during Pregnancy and Menstrual Cycle in Healthy Women

Citation Martínez‐García EA, Sánchez‐Hernández PE, Chavez‐Robles B, Nuñez‐Atahualpa L, Martín‐Márquez BT, Arana‐Argaez VE, García‐Iglesias T, González‐López L, Gamez‐Nava JI, Petri MH, Velazquez‐Rodriguez J, Salazar‐Paramo M, Davalos‐Rodriguez IP, Daneri‐Navarro A, Vázquez‐Del Mercado M. The distribution of CD56^dimCD16⁺ and CD56^brightCD16^? Cells are associated with prolactin levels during pregnancy and menstrual cycle in healthy women. Am J Reprod Immunol 2011; 65: 433–437 Problem The pregnancy and menstrual cycle (MC) are the main physiologic events linked to the human reproduction. An adequate neuroendocrine axis is mandatory for the homeostasis in both events. To analyze the distribution of NK, T, Treg cells, expression of their receptors and to associate with hormone levels in pregnant and MC in healthy women. Method of Study We studied two groups of healthy women: 13 pregnant women followed up at 1st, 2nd and 3rd trimesters and 11 women in the 5th and 21st day of the MC. The distribution of NK, T, Treg cells population, expression of their receptors and hormone levels were quantified. Results In pregnant women, we found an association of NK cells CD56^dimCD16⁺ with prolactin levels. This finding was also was observed for CD56^brigthCD16^? being statistical significant during 1st trimester for both subpopulations. During MC, correlation of CD56^dimCD16⁺, CD56^brightCD16^? cells with prolactin in follicular and luteal phase was found. Conclusion This is the first report where these cell subpopulations have been analyzed prospectively. Even we can argue the random effect for the small number of women is interesting that prolactin showed the more consistent correlation with CD56^dimCD16⁺, CD56^brigthCD16^? cells during both events studied.     

Type I interferon potentiates T‐cell receptor mediated induction of IL‐10‐producing CD4+ T cells

Type I interferons (IFNs) have the dual ability to promote the development of the immune response and exert an anti‐inflammatory activity. We analyzed the integrated effect of IFN‐α, TCR signal strength, and CD28 costimulation on human CD4⁺ T‐cell differentiation into cell subsets producing the anti‐ and proinflammatory cytokines IL‐10 and IFN‐γ. We show that IFN‐α boosted TCR‐induced IL‐10 expression in activated peripheral CD45RA⁺CD4⁺ T cells and in whole blood cultures. The functional cooperation between TCR and IFN‐α efficiently occurred at low engagement of receptors. Moreover, IFN‐α rapidly cooperated with anti‐CD3 stimulation alone. IFN‐α, but not IL‐10, drove the early development of type I regulatory T cells that were mostly IL‐10⁺ Foxp3^? IFN‐γ^? and favored IL‐10 expression in a fraction of Foxp3⁺ T cells. Our data support a model in which IFN‐α costimulates TCR toward the production of IL‐10 whose level can be amplified via an autocrine feedback loop.