Genetics and strain distribution of concanavalin A-reactive Ly-2-, L3T4- peripheral precursors of autoreactive T cells

Extrathymic differentiation of a T cell bearing invariant V alpha 14J alpha 281 TCR

We found that a homogenous CD4-/CD8- T cell bearing an invariant TCR encoded by V alpha 14J alpha 281 with a one-base N-region is highly dominant in the periphery (2-3% in spleen). Surprisingly, the high expression of this invariant V alpha 14 TCR is a general phenomenon in all laboratory strains irrespective of MHC haplotype and in some wild mouse subspecies. The majority of V alpha 14+ TCR is associated with J alpha other than J alpha 281 during the neonatal stage, after which the frequency of invariant V alpha 14J alpha 281 TCR expression increases with time reaching a maximum at around 5-8 weeks after birth. The dominant expression of V alpha 14J alpha 281 TCR is found in both euthymic and athymic mice. These results indicate that homogenous V alpha 14J alpha 281 T cells are positively selected in the periphery without thymic influence and that their VJ junction is important for positive selection. We also demonstrate that V alpha 14+ TCR gene rearrangements take place at extrathymic sites, such as bone marrow, liver, and intestine, since frequent nonproductive V alpha 14 TCR products and V alpha 14-J alpha 281 gene mediated signal sequences in circular DNA are detected as a result of TCR rearrangements in extrathymic tissues rather than in the thymus. This indicates the extrathymic development of V alpha 14J alpha 281 T cells. Furthermore, the biological roles of homogenous T cells bearing V alpha 14J alpha 281 TCR and the human counterpart of this invariant TCR are also discussed.

Analysis of T cell antigen receptor (TCR) expression by human peripheral blood CD4-8- alpha/beta T cells demonstrates preferential use of several V beta genes and an invariant TCR alpha chain

CD4-CD8- (double negative [DN]) alpha/beta T cells are a largely uncharacterized subpopulation of unknown function. To investigate whether these cells are selected to recognize particular antigens or antigen-presenting molecules, DN alpha/beta T cells were purified from the peripheral blood of five normal donors and their T cell receptor (TCR) alpha and beta chains were examined. Random cloning of TCR alpha chains by single-sided polymerase chain reaction (PCR) amplification identified an invariant rearrangement between V alpha 24 and J alpha Q, with no N region diversity, which was expressed preferentially by DN alpha/beta T cells from all donors. Random cloning also identified a precise V alpha 7.2-J alpha (IGRJa14) rearrangement, with two variable amino acids encoded in the V-J junction, which was enriched in the DN alpha/beta T cell preparations from some, but not all, donors. Analysis of TCR beta chains by quantitative PCR amplification demonstrated that the expression of four V beta gene families, V beta 2, 8, 11, and 13, was markedly increased in these DN alpha/beta T cell preparations. The expression of particular TCRs by DN alpha/beta T cells from multiple donors indicates that these cells, or at least a subpopulation of cells with this phenotype, recognize a limited spectrum of antigens and suggests that they may use nonpolymorphic antigen-presenting molecules.

Quantitative and functional analyses of spleen and in situ islet immune cells before and after diabetes onset in the NOD mouse

Cytofluorometric analysis using specific monoclonal antibodies directed against the T cell antigens Thy-1.2, CD4, CD8, CD4V beta(8.1 + 8.2 + 8.3), and the antigen Mac-1 expressed by mature macrophages and NK cells were used to characterize and quantify the phenotypes of (1) unfractionated and Percoll gradient fractionated in situ islet immune cells isolated from prediabetic and diabetic female NOD mouse spleens. We found in prediabetic female mice that the majority (approximately 70%) of the in situ islet immune cells were Thy-1.2 positive T cells. CD4 positive T cells (approximately 40%) were the most abundant phenotype together with double negative T cells (approximately 20%). The percentage of CD8 positive T cells were approximately 10%, and only approximately 4% of the immune cells were Mac-1 positive. The percentages of CD4V beta (8.1 + 8.2 + 8.3) positive and double negative T cells in diabetic spleens were significantly higher in comparison to prediabetic spleens. In C57B1/6J control nondiabetic mice the percentage of double negative T cells in the spleens was significantly 4-fold lower when compared to diabetic NOD spleens. The specific cytolytic activity mediated by in situ islet immune cells against 51Cr-labeled dispersed syngeneic single-cell islet cells at an effector to target ratio of 20 was twenty- to thirty-fold higher than that mediated by prediabetic splenic lymphoid cells. It is concluded that prediabetic NOD mouse in situ islet immune cells are mostly CD4 positive and double negative T cells, and that CD4 and CD8 positive T cells in the intra-islet infiltrate warrants further evaluation as potential effector T cells in target beta-cell destruction.

T gamma delta cells and their subsets in blood and synovial tissue from rheumatoid arthritis patients

We have examined the frequencies of T gamma delta cells in blood, synovial fluids, and synovial membranes of patients with rheumatoid arthritis (RA) and in blood from age-matched controls. Immunocytochemical and immunohistochemical techniques were used with monoclonal antibodies BB3 and A13 to define a major and minor blood subset of T gamma delta cells respectively. Together, these antibodies identify the majority (if not all) of the peripheral blood T gamma delta cells. Significantly lower levels of T gamma delta cells were found in the blood of RA patients compared with controls, whilst higher but not significant numbers were found in the synovial fluids of paired samples. Scattered T gamma delta cells were found only in some synovial membranes with a distribution similar to the T alpha beta cells. Analysis of the two different T gamma delta-cell subsets indicated a ratio of BB3 to A13 of about 5:1 in control and RA blood. However, this ratio was less than 1:1 in the RA synovial fluids and membranes. The migratory nature of the A13+ cells could account for their predominance in these sites. The possible pathological significance of these cells in the rheumatoid synovial fluid and synovial membranes is discussed.

Induction of interleukin-3 by interleukin-1 in the absence of other exogenous stimuli

We have previously reported that lipopolysaccharide (LPS) could induce the production of interleukin-3 (IL-3) by mouse spleen cells. In the present study, we show that recombinant human interleukin-1, in the absence of other stimuli, is able to induce the production of IL-3. IL-3 was detected in the supernatants of adult, although neither in young nor in nude mouse splenocytes and was assessed by its capacity to support the growth of the IL-3-dependent FDC-P2 cell line. The presence of IL-3 was antigenically confirmed with a monoclonal anti-IL-3 antibody. Both recombinant IL-1 alpha and IL-1 beta had similar potential for inducing IL-3 production. IL-3 activity was detected in the supernatants of cells cultured in the presence of 100 pg/ml IL-1; maximal IL-3 levels were obtained with 10-30 ng/ml IL-1. Kinetic studies of IL-1-induced IL-3 production indicated that 4-6 days of culture were required for optimal production, whereas 1-2 days were sufficient in cultures stimulated with concanavalin A. Recombinant IL-6 failed to induce significant amounts of IL-3, and TNF alpha induced only weak IL-3 production. GM-CSF but not M-CSF could lead to the appearance of IL-3 in spleen cell culture supernatants. Removal of macrophages decreased the production of IL-3 induced by LPS and GMF-CSF though did not affect the IL-3 production induced by IL-1. This observation suggests that IL-1 production might be an intermediate event in IL-3 production induced by LPS and GM-CSF through the activation of macrophages. IL-3 was detected in culture supernatants of B-cell-depleted splenocytes indicating that T-cells were the source of IL-3. Surprisingly T-cell-depleted populations could also produce IL-3 upon IL-1 stimulation. Preliminary experiments with an autoreactive CD4- CD8- V beta 8+ clone suggested that these cells might also be involved in the described IL-3 production.

T cell receptor V beta genes expressed by IgG anti-DNA autoantibody-inducing T cells in lupus nephritis: forbidden receptors and double-negative T cells

In the (SWR x NZB)F1 (SNF1) model of lupus nephritis, pathogenic variety of IgG anti-DNA autoantibodies are induced by certain T helper (Th) cells that are either CD4+ or CD4-CD8- (double negative; DN) in phenotype. From the spleens of eight SNF1 mice with lupus nephritis, 149 T cell lines were derived and out of these only 25 lines (approximately 17%) were capable of augmenting the production of pathogenic anti-DNA autoantibodies. Herein, we analyzed the T cell receptor (TcR) V beta genes used by 16 such pathogenic autoantibody-inducing Th cell lines. Twelve of the Th lines were CD4+ and among these five lines expressed V beta 8 (8.2 or 8.3). The V beta 8 gene family is contributed by the NZB parent to the SNF1 mice, since it is absent in the SWR parental strain. Three other CD4+ Th lines expressed V beta 4, another was V beta 2+ and one line with poor autoantibody-inducing capability expressed V beta 1. Four autoantibody-inducing Th lines from the SNF1 mice had a DN phenotype and these lines were also autoreactive, proliferating in response to syngeneic spleen cells. Among these DN Th lines, two expressed V beta 6 and one expressed V beta 8.1 TcR. Both of these are forbidden TcR directed against Mls-1a (Mlsa) autoantigens expressed by the SNF1 mice and such autoreactive T cells should have been deleted during thymic ontogeny. Thus, the DN Th cells of non-lpr SNF1 mice are different from the DN cells or MRL-lpr which lack helper activity and do not express forbidden TcR. The spleens of 6 out of 19 nephritic SNF1 animals tested also showed an expansion of forbidden autoreactive TcR+ cells that were mainly DN. Two of these animals expressed high levels of V beta 6 (anti-Mlsa) and V beta 11 (anti-I-E) TcR+ cells, three others had high levels of V beta 11+ cells alone and one animal had an expanded population of V beta 17a+ (anti-I-E) cells. The I-E-reactive TcR again should have been eliminated in the SNF1 thymus, since they express I-E molecules contributed by the NZB parent. The SWR parents of SNF1, are I-E-; moreover, they lack the V beta 11 gene but they express V beta 17a in peripheral T cells. Whereas the NZB parents are I-E+, they lack a functional V beta 17a gene and they delete mature V beta 11+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoreactive T cells in normal mice: unrestricted recognition of self peptides on dendritic cell I-A molecules by CD4-CD8- T cell receptor alpha/beta+ T cell clones expressing V beta 8.1 gene segments

CD4-CD8- double-negative (DN) and CD4+CD8- T cell clones were derived from splenic precursors resistant to killing by anti-Thy-1, -CD5, -CD4 and -CD8 monoclonal antibodies and complement. Both DN and CD4+ clones express functional T cell receptor (TcR) alpha/beta and exhibit strong autoreactivity in vitro. DN cells can be induced to proliferate by dendritic cells (DC) of all haplotypes tested, although this activation is inhibited by antibodies specific for I-A determinants expressed on the stimulatory DC. In contrast, CD4+ clones only respond to syngeneic or I-Ad-compatible DC. Both DN and CD4+ autoreactive clones do not proliferate when cultured with class II+ H-2d normal or tumor macrophages and B cell lines or with class II-transfected L cells, suggesting that these cells recognize self peptides only present on the surface of DC. Despite their phenotype resembling that of immature thymocytes and their inability to interact directly with B lymphocytes, DN cloned T cells, like CD4+ T cells, exhibit nonspecific helper functions and can induce polyclonal B cell proliferation and differentiation. DN TcR alpha/beta+ peripheral T cells represent, like TcR gamma/delta+ lymphocytes, a new T cell subset physiological role whose remains to be defined.

Novel origin of lpr and gld cells and possible implications in autoimmunity

The lpr and gld mutations are prime examples of single-gene defects associated with expansion of a unique double-negative (CD4-8-), T-cell receptor alpha:beta + cell population and heightened polyclonal and autoimmune responses. The exact origin of these autoimmunity-inducing/enhancing T cells remains controversial. Here, we review the characteristics of the lpr and gld mutations, and speculate on the possible relationship of these cells to normal thymic differentiation pathways. We argue that mounting evidence now supports the existence of a CD4/CD8-loss pathway of late thymic differentiation, responsible for the origin of both normal and lpr/gld double-negative alpha:beta + cells. We further speculate that downregulation of CD4 and CD8 accessory molecules on thymocytes with moderately autoreactive T-cell receptors is involved in selecting cells, including lpr/gld precursors for this pathway. Escape of a large number of such autoreactive cells from thymic elimination might be an important contributory factor to the pathogenesis of autoimmunity.

Tolerance-related V beta clonal deletions in normal CD4-8-, TCR-alpha/beta + and abnormal lpr and gld cell populations

We have analyzed tolerance-related clonal deletion of Mls-and I-E-reactive thymocytes at the RNA level using a multi-V beta probe RNAse protection assay, and used this phenomenon to identify the maturation stage of the abnormally expanded CD4-8-, TCR-alpha/beta + subset in lpr and gld homozygous mice, and of the phenotypically similar minor thymocyte subset found in normal mice. Essentially complete V beta clonal deletions were detected in lpr and gld cells of all appropriate background strains. Substantial, but not complete, V beta clonal deletions were also detected in the CD4-8- TCR-alpha/beta + subset of normal mice. Since expression of CD4/CD8 is required for V beta clonal deletions to occur, we conclude that lpr and gld cells, and at least a portion of CD4-8- TCR-alpha/beta + thymocytes in normal mice, are derived by secondary loss of CD4/CD8 accessory molecules from more mature CD4+8+ precursors. One possible interpretation of these findings is that such CD4/CD8 loss may affect a class of self-reactive thymocytes that have escaped direct clonal deletion. Exportation and expansion of such cells in the periphery may be an important contributory factor in the induction of systemic autoimmunity.

Isolation of CD4- CD8- mycobacteria-reactive T lymphocyte clones from rheumatoid arthritis synovial fluid

The majority of peripheral T cells express a heterodimeric, alpha/beta T-cell receptor, which recognizes specific antigenic peptides bound to self major histocompatibility complex (MHC) molecules, and either the CD4 or CD8 surface markers. An additional subset of T cells, whose physiological function is unknown, express a distinct CD3-associated receptor composed of gamma and delta chains. This subset includes cells lacking both CD4 and CD8 surface markers, which may be involved in autoimmunity. The recognition specificity of the gamma/delta receptors is not well characterized and has been defined in only one case to date, a murine cell line which shows MHC-linked specificity. In this report, we describe the isolation of CD4- CD8-, gamma/delta TCR bearing T cell clones from the synovial fluid of a rheumatoid arthritis patient. These T cell clones respond specifically to mycobacterial antigens without MHC restriction.