Activation of Vgamma9Vdelta2 T cells by non-peptidic antigens induces the inhibition of subgenomic HCV replication

Hepatitis C virus (HCV) has evolved complex strategies to evade host immune responses and establish chronic infection. Since human Vgamma9Vdelta2 T lymphocytes play a critical role in the immune response against viruses, we analyzed their antiviral functions on Huh7 hepatoma cells carrying the subgenomic HCV replicon (Rep60 cells). In a transwell culture system, Rep60 cells were co-cultured with either PBMCs or highly purified gammadelta T cells stimulated by non-peptidic antigens. Vgamma9Vdelta2 T cell activation was associated with a dramatic reduction of HCV RNA levels. Neutralizing antibodies targeting IFN-gamma revealed a critical role for this cytokine in the inhibition of HCV replication. Interestingly, drugs already in clinical use, such as Phosphostim and Zoledronate, known to activate gammadelta T cells, were shown to induce the inhibition of HCV replication mediated by Vgamma9Vdelta2 T cells of HCV patients. Our data suggest that the therapeutic activation of Vgamma9Vdelta2 T lymphocytes may represent an additional strategy to inhibit HCV replication and to restore a Th1-oriented immune response in HCV-infected patients.     

A potential role for protein tyrosine kinase p56(lck) in rheumatoid arthritis synovial fluid T lymphocyte hyporesponsiveness

Rheumatoid arthritis (RA) synovial fluid (SF)-T lymphocytes appear relatively inactive in situ and respond only weakly to diverse stimuli ex vivo. To characterize the molecular defects underlying this hyporesponsiveness we analyzed the expression level of several proteins involved in TCR-proximal signal transduction. As compared to peripheral blood (PB)-T lymphocytes, SF-T cells from some (but not all) of the patients analyzed expressed lower levels of TCRalphabeta, CD3epsilon, TCRzeta, p56(lck) and LAT, while p59(fyn), phospholipase C-gamma1 and ZAP-70 expression was unaltered. Semi-quantitative analysis of T cells from several patients revealed that the degree of TCRzeta chain and p56(lck) modulation correlated statistically significantly with the level of SF-T cell hyporesponsiveness. The differential reactivity of p56(lck) specific monoclonal and polyclonal antibodies in SF-T but not PB-T lymphocytes indicated that p56(lck) modulation consists of a conformational change rather than loss of expression. Our results indicate that multiple signaling molecules can be modulated in RA SF-T cells and show for the first time a direct quantitative correlation between T cell hyporesponsiveness and modulation of TCRzeta and of p56(lck), a critical protein tyrosine kinase required for T cell activation.     

Expression of a fetal gamma delta T-cell receptor in adult mice triggers a non-MHC-linked form of selective depletion.

Day 14 fetal thymocytes and adult dendritic epidermal T cells (dEC) of all mouse strains express a characteristic non-polymorphic gamma delta T-cell receptor which is rarely found in the adult thymus or lymph nodes. We have made transgenic mice expressing this particular set of receptors on T cells in C3H and C57BL/6 mice. In adult mice of the latter strain, a dramatic depletion of transgene expressing T cells occurs and this effect is primarily mediated by thymic radiosensitive cells. The depletion is genetically dominant but not MHC-linked with major factor(s) mapping to chromosome 18. Taken together, our results show that strain-specific developmental changes in the thymic environment may play a role in shaping the gamma delta TCR repertoire.     

Gamma delta T cells expressing CD8 or CD4low appear early in murine foetal thymus development.

Three-colour flow cytometry was used to study the distribution of TCR gamma delta+ cells among CD4+CD8-, CD4-CD8+, CD4+CD8+, and CD4-CD8- cell populations during thymic development. Thymocytes were obtained either directly from embryos at different stages of gestation (ex vivo) or from organ cultures maintained in vitro. In both cases, TCR gamma delta+ cells were found predominantly among the double negative (CD4-CD8-) and CD8 single positive subsets. These cells were actively dividing as demonstrated by 7 amino actinomycin D (7AAD) labelling. A small population of TCR gamma delta+ cells expressing low levels of CD4 was identified early and transiently (days 15-18) during development, but this subset was rare in the adult thymus. In newborn mice, adult mice, and late during organ culture, TCR gamma delta+ cells were found mainly within the CD4-CD8- compartment of thymocytes, although a minor population of CD8+ cells (5-10%) bearing gamma delta receptor was routinely observed. In contrast, few gamma delta cells were contained among the CD4+CD8+ subset at any timepoint studied. These data highlight differences between the ontogeny of alpha beta and gamma delta cells in the thymus, and suggest that a CD4+CD8+ intermediate may not be a requisite for the intrathymic differentiation of murine gamma delta T cells.     

A role for BP-3/BST-1 antigen in early T cell development

In the mouse thymus, pre-T cells are defined by their CD3^–CD4^–CD8^–triple-negative, CD44^10/– CD25⁺ phenotype. We made a ratmAb IF-7, that, among all Tcell subsets analyzed, reacted exclusivelywith pre-T cells. Molecular cloning revealed that the antigenrecognized by IF-7 was identical to BP-3/BST-1, a glycosyl-phosphatidylinositol-linked,CD38-related molecule previously described asa possible co-activationmolecule of pre-B cells. We found that IF-7 cross-linking enhancesthe proliferative response ofsorted pre-T cells to anti-CD3stimulation. In addition, IF-7 enhances and accelerates thedevelopment of fetal thymic organ culture (FTOC), although the lineage is unaffected by the treatment. In addition, sortedIF-7⁺ pre-T cells give preferentially rise to ß TCR⁺thymocytes in FTOC. Our observations strongly suggest that BP-3/BST-1is implicated in both early B and T cell growth and development,and is an early marker for the ß lineage.     

Recognition mechanism of non-peptide antigens by human gammadelta T cells

The majority of gammadelta T cells in adult human blood exhibit Vgamma2/Vdelta2-TCR and specifically respond to various kinds of non-peptide antigens. In this study, we comparatively analyzed the CDR3 repertoires of Vgamma2-gamma and Vdelta2-delta chain genes in the adult and cord blood. It was confirmed that the vast majority of adult gammadelta T cells exhibited Vgamma2-gamma chains bearing a Jgamma1.2 segment with no or short N-region and Vdelta2-delta chains with a conserved hydrophobic residue (leucine, valine or isoleucine) at position 97 encoded by N-region of Vdelta/Jdelta junction (deltaL97). The cord blood cells stimulated with pyrophosphomonoester antigen in vitro showed preferential expansion of the gammadelta T cells expressing Vgamma2- and Vdelta2-TCR chains with these structural features as compared with those stimulated with a polyclonal mitogen phytohemagglutinin. TCR gene transfer studies indicated that alanine substitution of lysine at position 108 in Jgamma1.2 (gammaK108) or deltaL97 abrogated the responsiveness of Vgamma2/Vdelta2-TCR to all kinds of the non-peptide antigens without affecting the response to anti-CD3 antibody. Furthermore, alanine substitution of arginine at position 51 in Vdelta2 segment (deltaR51) adjacent to gammaK108 in the Vgamma2/Vdelta2-gammadelta TCR also abolished the antigen responsiveness. These results strongly suggested that a hydrophobic and two cationic residues (deltaL97, gammaK108 and deltaR51) clustered in a particular topology at the surface edge of the pocket structure of Vgamma2/Vdelta2-gammadelta TCR played essential roles in the recognition of non-peptide antigens.     

Estrogen receptors alpha and beta (ERalpha and ERbeta) and androgen receptor (AR) in human sperm: localization of ERbeta and AR in mitochondria of the midpiece

BACKGROUND: The central role of estrogens and androgens in the male reproductive system has focused attention on the presence and distribution of their cognate receptors [estrogen receptor (ER) alpha, ERbeta and androgen receptor (AR)] in male reproductive tissues and cells. Since the presence of steroid hormone receptors in mitochondria of mammalian cells has been well documented, we investigated the possibility of mitochondrial localization of sex steroid hormone receptors in sperm. METHODS AND RESULTS: Applying immunofluorescence labelling and confocal laser scanning microscopy we show that the estrogen receptor beta and the AR of human sperm are specifically enriched in the midpiece, at the site of the mitochondria, which were visualized by labelling with the vital dye CMX. Nuclear and mitochondrial localization of AR was also detected in LnCap human prostate cancer cells. Differentially, most of the ERalpha immunostaining is in the form of a compact zone at a region corresponding to the equatorial segment of the upper post-acrosomal region of the sperm head. Immunoblotting experiments using sperm extracts revealed the presence of a 66 and a 45 kDa protein reacting with the ERalpha antibody, one 64 kDa protein reacting with the ERbeta antibody and a 110 and a 90 kDa protein reacting with the antibody against AR. CONCLUSIONS: Our findings suggest that the differential localization of AR and ER isoforms in human sperm reveals distinct roles of these receptors in the physiology of sperm cells and, perhaps, also in the process of fertilization.     

High frequency of circulating gamma delta T cells with dominance of the v(delta)1 subset in a healthy population

TCR gamma delta(+) cells constitute <5% of all circulating T cells in healthy, adult Caucasians, and V(delta)1(+) cells constitute a minority of these cells. In contrast to TCR alpha beta(+) cells, their repertoire is selected extrathymically by environmental antigens. Although increased frequencies of V(delta)1(+) cells are found in several diseases, their function remains obscure. Here we show that the frequency of peripheral blood gamma delta T cells in healthy West Africans is about twice that of Caucasians, mainly due to a 5-fold increase in V(delta)1(+) cells, which is consequently the dominant subset. No age dependency of V(delta)1 frequencies was identified and the V(delta)1(+) cells in the African donors did not show preferential V(gamma) chain usage. Analysis of the CDR3 region size did not reveal any particular skewing of the V(delta)1 repertoire, although oligoclonality was more pronounced in adults compared to children. The proportions of CD8(+), CD38(+) and CD45RA(hi)CD45RO(-) cells within the V(delta)1(+) subset were higher in the African than in the European donors, without obvious differences in expression of activation markers. No significant correlations between levels of V(delta)1(+) cells and environmental antigens or immunological parameters were identified. Taken together, the evidence argues against a CDR3-restricted, antigen-driven expansion of V(delta)1(+) cells in the African study population. Our study shows that high frequencies of TCR gamma delta(+) cells with dominance of the V(delta)1(+) subset can occur at the population level in healthy people, raising questions about the physiological role of V(delta)1(+) T cells in the function and regulation of the immune system.     

Maternal serum levels of interferon-gamma and interleukin-2 soluble receptor-alpha predict the outcome of early IVF pregnancies

BACKGROUND: Elevated maternal serum levels of interleukin-2 soluble receptor-alpha (IL-2 sRalpha), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) have been associated with pregnancy loss. The aim of our study was to evaluate the predictive value of these cytokines in the outcome of early IVF pregnancies. METHODS: One hundred and fifty-nine consecutive IVF patients who were subsequently diagnosed to have a biochemical pregnancy (n = 23), a first-trimester miscarriage (n = 19) or a normal term delivery (n = 117) were included in this study. Serum was collected from the initial pregnancy test, 11 days after a day 3 embryo transfer, and all samples were analysed for IL-2 sRalpha, TNF-alpha and IFN-gamma by commercially available enzyme-linked immunosorbent assay (ELISA) kits. RESULTS: IL-2 sRalpha levels were significantly higher in patients with an early pregnancy loss compared with patients with a normal term delivery (849.5 +/- 69.6 versus 693.5 +/- 31.2 pg/ml, P = 0.02), and a cut-off point of IL-2 sRalpha >1000 pg/ml predicted a poor pregnancy outcome (44.4 versus 22.7% pregnancy loss, IL-2 sRalpha >or=1000 versus IL-2 sRalpha <1000 pg/ml; P = 0.02). IFN-gamma-positive patients had twice the risk for poor IVF pregnancy outcome compared with IFN-gamma-negative subjects (40.8 versus 20.0%, respectively; P < 0.02), including a significantly lower implantation rate (37.6 +/- 0.05 versus 50.0 +/- 0.03%, respectively; P = 0.02). There was no difference in pregnancy outcome based upon serum levels, or the ability to detect the presence of TNF-alpha. No differences in levels of these cytokines were found based on the aetiology of the patients' infertility. CONCLUSIONS: Elevated maternal serum levels of IL-2 sRalpha and IFN-gamma as early as 11 days after embryo transfer are associated with poor IVF pregnancy outcome.     

A large proportion of bovine T cells express the gamma delta T cell receptor and show a distinct tissue distribution and surface phenotype

The numbers, phenotype, and tissue distribution of gamma delta T cells in cattle were studied using two monoclonal antibodies (mAbs) which react with the bovine gamma delta T cell receptor (TCR). Both mAbs stained 20-40% of T cells in peripheral blood, and immunoprecipitated molecules of 44 and 36 kd (reduced) and 70-80 kd (non-reduced). In cattle the majority of circulating gamma delta T cells showed a distinct surface phenotype; they expressed T19, a 215 kd molecule described in sheep and cattle which marks only gamma delta T cells. Bovine gamma delta T cells were also CD2-, CD4-, and mostly CD8-, and failed to express CD6, a molecule possibly involved in T cell activation. The distribution of gamma delta T cells in cattle lymphoid tissues differed markedly from that in humans, in that bovine gamma delta T cells were concentrated around lymph node trabeculae and were usually sparse or absent from the B cell and T cell domains of lymph nodes. Like most other species studied, gamma delta T cells in cattle were localized to epithelial surfaces, particularly within the skin and intestine, indicating that it was at these sites where gamma delta T cells functioned. Our results provide further evidence for the unusual localization, recirculation pattern, and phenotype of gamma delta T cells, and also show that some features of gamma delta T cells can differ quite markedly from species to species.     

Comprehensive phenotypic analysis of the gut intra-epithelial lymphocyte compartment: perturbations induced by acute reovirus 1/L infection of the gastrointestinal tract

Intestinal intra-epithelial lymphocytes (IELs) form a highly specialized lymphoid compartment. IELs consist primarily of T cells that are dispersed as single cells within the epithelial cell layer that surrounds the intestinal lumen. These lymphocytes along with lamina propria lymphocytes are considered to play an important role in the regulation of immune responses. IELs are heterogeneous with regard to phenotype, and they contain sub-populations with diverse functions. In our most recent study, we found that intra-duodenal inoculation of mice with reovirus serotype 1/strain Lang (reovirus 1/L) induced expression of both germinal center and T cell antigen and CD11c on IELs suggesting these cells to be the recently stimulated cells in gut mucosal tissue. We also demonstrated that IELs from these mice when cultured in vitro in the presence of reovirus 1/L-pulsed antigen-presenting cells generated reovirus 1/L-specific MHC-restricted CTL whose function was mediated utilizing perforin, Fas-FasL and TRAIL mechanisms. This present study provides a comprehensive analysis of the diverse subsets of IELs, which function with other mucosal cells to provide a strong, protective immunity in a highly regulated fashion inside the microenvironment of the intestinal epithelium. We demonstrated that the IEL population contains both thymus-dependent (TD) and thymus-independent (TI) lymphocytes in mice and that a complex phenotype is present when sub-populations are analyzed for TCR, Thy-1, CD4, CD8 and B220 expression in a comprehensive manner. In reovirus 1/L-inoculated mice, we found a decrease in the TI population and an increase in the TD population characterized by significant alterations in various sub-populations. This increase was largely due to an increase in CD4(+), CD8(+) and CD4/CD8 double-positive sub-populations of TD IELs. Intracellular cytokine analysis demonstrated induction of IFN-gamma and an increase in effector/cytotoxic CD8 and CD4 cells after reovirus 1/L infection. These results suggest that TD IELs may play an important role in the clearance of reovirus 1/L infection from gut.     

Lymph node homing cells biologically enriched for {gamma}{delta} T cells express multiple genes from the T19 repertoire

Sheep T cells have been shown serologically to express T19,a membrane protein of 180–200 kDa which is a member ofthe scavenger receptor superfamily. Previous work from thislaboratory resulted in the detection of a multigene family ofT19-like genes in the sheep genome. In this study nucleotidesequences from several T19 genes were determined and are reportedalong with the corresponding segments of a number of expressedmRNA molecules. A segment of a single sheep T19-like gene wassequenced and these data, along with the corresponding sequencesfrom cloned T19-like cDNA molecules from sheep and cow, wereused to design an ollgonucleotide primer system suitable foramplification of corresponding segments of many T19 genes andtheir cDNAs. Between 30 and 40% of cloned T19 genes were amenableto amplification using the selected primers, and sequence analysisof cloned PCR products confirmed that different T19 genes encodeunique amino acid sequences. The expression of multiple T19genes was established using cDNA molecules obtained from a singlesample of sheep lymphocyte mRNA. The possible role of the T19family of genes is discussed.     

Immunology: Autoimmunity to spermatozoa, asymptomatic Chlamydia trachomatis genital tract infection and {gamma}{delta} T lymphocytes in seminal fluid from the male partners of couples with unexplained infertility

The relationship between an undetected, asymptomatic Chlamydiatrachomatis genital tract infection, the concentration of andb T cells in semen and sperm autoimmunity was examined in 48male partners of couples with unexplained infertility. ImmunoglobulinA (IgA) antibodies to C.trachomatis were detected in seminalfluids from 14 (29.2%) of the men. Only four of these were positivefor circulating anti-chlamydial IgA, suggesting that the stimulusfor antibody production was within the genital tract. In contrast,four men were positive for anti-chlamydial IgG in their semen;all were also seropositive for anti-chlamydial IgG. T lymphocytesbearing the and antigen receptors were present in every semensample. Men with seminal anti-chlamydial IgA, however, had significantly(P = 0.035) elevated semen T cell concentrations (median 3100cells/ml) than did men lacking this antibody (median 1400 cells/ml);concentrations of T cells were comparable in both groups. Genitaltract sperm autoimmunity, as shown by antibodies bound to motileejaculated spermatozoa, was detected in 13 (27.1%) men. Thepresence of these antibodies was associated with elevated concentrationsof both (median 4200 versus 700 cells/ml) and (median 5000versus 850 cells/ml) T cells (P = 0.0002 and 0.0001 respectively).Men with antisperm antibodies only in their serum had seminalT cell concentrations comparable with men testing negative forantisperm antibodies. Anti-chlamydial IgA was identified insemen from four of 10 men with IgA bound to their spermatozoaand in none of the men with only spermatozoabound IgG. Therewas no relationship between sperm quality and the occurrenceof seminal IgA antibodies to either C.trachomatis or spermatozoa.An asymptomatic C.trachomatis infection activates T cells withinthe male genital tract, which may lead to antisperm antibodyformation and immune-mediated infertility.     

Phenotypic and functional properties of murine {gamma}{delta} T cell clones derived from malaria immunized, {alpha}{beta} T cell-deficient mice

Six murine T cell clones expressing TCR were generated frommalaria immunized, ß T celldeficient mice. Phenotypiccharacterization of these clones has revealed that, in contrastto conventional ß T cells, there is a considerabledegree of heterogeneity among these clones with regard to theirsurface markers and their lymphokine profile. One clone wasfound to display significant anti-parasite activity in vivoupon adoptive transfer. We attempted to determine whether theprotective clone differs in one or more key characteristicsfrom the non-protective clones. Although no obvious patternpeculiar to the protective clone was observed, it appears thatmore than one parameter may, in combination, define a distinctprotective phenotype, and thus explain the functional differencebetween the protective and non-protective clones.     

The appearance and role of gamma delta T cells in the peritoneal cavity and liver during primary infection with Listeria monocytogenes in rats.

We have previously reported that gamma delta T cells play important roles in protection during the early stage of infection with Listeria monocytogenes in mice. To generalize the protective roles of gamma delta T cells in listerial infection to different species, we examined the appearance of gamma delta T cells during infection with L. monocytogenes in Fisher F344 rats. The numbers of bacteria in the peritoneal cavity and liver increased to a maximum level on day 3 and then decreased to an undetectable level by day 10 after an intraperitoneal infection with a sublethal dose (1 x 10(8)) of viable L. monocytogenes in rats. CD3+ alpha beta- T cells in the peritoneal cavity and liver began to increase on day 3, reached a maximum level on day 6, and thereafter decreased gradually by day 10 after infection. Northern blot analysis confirmed that the CD3+ alpha beta- T cells expressed TCR delta and gamma gene messages. In vivo treatment with anti-TCR alpha beta mAb, which suppressed most of the alpha beta T cells in the periphery and impaired resistance during the late stage of listerial infection, did not affect the host defense by day 6 after infection. A significantly increased number of gamma delta T cells was detected in the peritoneal cavity of the TCR alpha beta-suppressed rats on day 6 after infection. These results suggest that the early appearing gamma delta T cells may contribute to the host defense at a relatively early stage during listeriosis in rats.     

Transient hypogonadotrophic hypogonadism in males with acute toxoplasmosis: suppressive effect of interleukin-1 beta on the secretion of GnRH

BACKGROUND: In September 2002, an outbreak of toxoplasmosis was noted in a male boarding high school on the Aegean coast of Turkey. We have focused our efforts to investigate the sex hormones in this population. METHODS: Blood samples were collected from 40 male patients, 17-18 years old, who also had positive titres of antibody to Toxoplasma gondii. Serum FSH, LH, free testosterone (FT), total testosterone (TT), interferon-gamma (IFN-gamma), interleukin-1beta (IL-1beta) and macrophage-inflammatory protein-1alpha (MIP-1alpha) concentrations were measured in all patients and 20 control subjects. Initially, the patients were divided on the basis of the levels of sex hormones into the following groups: patients who had normal sex hormone levels (n = 31) as group A and patients with low sex hormone levels (n = 9) as group B. RESULTS: IL-1beta levels were found to be higher in group B patients than group A. The levels of IL-1beta correlated significantly in a negative manner with FSH, LH, FT and TT in all patients with acute toxoplasmosis (n = 40). CONCLUSIONS: Acute toxoplasma infection may cause temporary hypogonadotrophic gonadal insufficiency regardless of the course of the disease.     

Distribution of fetal erythroblasts enriched from maternal blood in multifetal pregnancies

BACKGROUND: The aim of this study was to establish the frequency of fetal cells in the maternal blood of multifetal pregnancies and compare this figure with singleton pregnancies. METHODS: We obtained maternal blood from 31 pregnancies with 2-6 fetuses at 11-16 weeks gestation and from 50 normal singleton controls (11-14 weeks gestation). Fetal erythroblasts were isolated from maternal blood using triple density gradient separation and anti-CD71 magnetic cell-sorting techniques. The enriched erythroblasts were stained with Kleihauer-Giemsa and with fluorescent antibodies for the zeta (zeta), epsilon (epsilon) and gamma (gamma) globin chains. The percentage of fetal cells positive for each stain was calculated. Fluorescence in-situ hybridization (FISH) for X and Y chromosomes was also performed. RESULTS: The percentage of erythroblasts enriched from maternal blood that stained positive for zeta, epsilon and gamma globin chains and with Kleihauer-Giemsa was significantly higher in the multifetal compared with singleton pregnancies. The median enriched percentage of positively stained erythroblasts was about three times higher in the twin than in singleton pregnancies (P < 0.0001), nearly twice as high in the triplet than in twin pregnancies (P < 0.01) and five times higher in the triplet than singleton pregnancies (P < 0.0001). FISH for Y chromosome confirmed the increase in fetal cell proportion in the multifetal pregnancies. CONCLUSIONS: These findings suggest that there is an increase in the physiological feto-maternal cell trafficking in multifetal pregnancies compared with singleton pregnancies, which is likely to be due to the increased placental surface area and vasculature.     

Gammadelta T cells increase with Mycobacterium avium complex infection but not with tuberculosis in AIDS patients.

The aim of the present study was to better characterize the expansion of double-negative (DN) T cells in vivo in AIDS patients and to ascertain the discrepant response of an immunodepressed immune system towards two distinct mycobacterial infections. In a large cohort of HIV-1 seropositive patients with low CD4(+) T cell counts (<100/mm(3)), we have recently reported on an expansion of DN T cells which was observed only in patients with disseminated Mycobacterium avium infection, toxoplasmosis and Kaposi sarcoma, but not in patients with tuberculosis. The potential differential gammadelta T cells response observed in vivo in AIDS patients with tuberculosis or disseminated M. avium complex infection was investigated by collecting the concomitant or the closest T lymphocyte counts performed within 2 weeks of bacterial diagnosis of 112 disseminated M. avium infection and 41 tuberculosis patients. The DN and gammadelta T cell percentages were different between the two groups (P < 10(-4)) and the expansion of this compartment was found only with disseminated M. avium infections. An analysis of the variable delta2 segment versus pan-delta bearing T cells ratio disclosed a predominance of non-V(delta)2 T cells in these patients whose average values were identical in both groups. It is therefore concluded that the difference seen between these two types of mycobacterial infections concerning the DN T cells only involved the gammadelta T cells although the mechanism of their preferential expansion in disseminated M. avium infections remains a matter of speculation.     

Monoclonal antibody against murine T cell receptor V alpha 14 cross-reacts with human CD3 epsilon and detects disulfide-linked dimeric form.

A monoclonal antibody against V14+ alpha-chain of murine T cell receptor (TCR) was established by fusing spleen cells from a rat immunized with a soluble chimeric TCR/IgG3 protein containing murine TCR V alpha 14J alpha 281 in place of the VHDHJH of an IgG3. lambda 1, and subjected to screening on a human transfectant (Jurkat variant) expressing the murine V14J281 alpha-chain. The anti-mouse V alpha 14 antibody precipitated TCR alpha beta molecules from Triton X-100-solubilized extracts of 125I-labeled murine thymocytes and spleen cells. Unexpectedly, the antibody showed cross-reactivity to the human CD3 epsilon molecule and detected a disulfide-linked 20 kDa dimeric form of human CD3 epsilon, which is a novel family component of the CD3 complex and is associated closely with the CD3 zeta-zeta homodimer as well as TCR alpha beta or TCR gamma delta.