T-cell receptor V beta repertoire expression in murine models of SLE

Autoimmunity-Basics and link with periodontal disease

Autoimmune reactions reflect an imbalance between effector and regulatory immune responses, typically develop through stages of initiation and propagation, and often show phases of resolution (indicated by clinical remissions) and exacerbations (indicated by symptomatic flares). The fundamental underlying mechanism of autoimmunity is defective elimination and/or control of self-reactive lymphocytes. Periodontal diseases are characterized by inflammatory conditions that directly affect teeth-supporting structures, which are the major cause of tooth loss. Several studies have demonstrated the involvement of autoimmune responses in periodontal disease. Evidence of involvement of immunopathology has been reported in periodontal disease. Bacteria in the dental plaque induce antibody formation. Autoreactive T-cells, natural killer cells, ANCA, heat shock proteins, autoantibodies, and genetic factors are reported to have an important role in the autoimmune component of periodontal disease. The present review describes the involvement of autoimmune responses in periodontal diseases and also the mechanisms underlying these responses.

Identification of systemically expanded activated T cell clones in MRL/lpr and NZB/W F1 lupus model mice

CD4(+) T lymphocytes play an important role in the pathogenesis of systemic lupus erythematosus (SLE). To characterize the clonal expansion of CD4(+) T cells in murine lupus models, we analysed the T cell clonality in various organs of young and nephritic MRL/lpr and NZB/W F1 mice using reverse transcription-polymerase chain reaction (RT-PCR) and subsequent single-strand conformation polymorphism (SSCP) analysis. We demonstrated that some identical T cell clonotypes expanded and accumulated in different organs (the bilateral kidneys, brain, lung and intestine) in nephritic diseased mice, and that a number of these identical clonotypes were CD4(+) T cells. In contrast, young mice exhibited little accumulation of common clones in different organs. The T cell receptor (TCR) V beta usage of these identical clonotypes was limited to V beta 2, 6, 8.1, 10, 16 and 18 in MRL/lpr mice and to V beta 6 and 7 in NZB/W F1 mice. Furthermore, some conserved amino acid motifs such as I, D or E and G were observed in CDR3 loops of TCR beta chains from these identical CD4(+) clonotypes. The existence of systemically expanding CD4(+) T cell clones in the central nervous system (CNS) suggests the involvement of the systemic autoimmunity in CNS lesions of lupus. FACS-sorted CD4(+)CD69(+) cells from the kidney displayed expanded clonotypes identical to those obtained from the whole kidney and other organs from the same individual. These findings suggest that activated and clonally expanded CD4(+) T cells accumulate in different tissues of nephritic lupus mice, and these clonotypes might recognize restricted T cell epitopes on autoantigens involved in specific immune responses of SLE, thus playing a pathogenic role in these lupus mice.

Acceleration of lpr Lymphoproliferative and Autoimmune Disease by Transgenic Protein Kinase CK2α

MRL-lpr/lpr mice have a Fas receptor mutation that leads to abnormalities of apoptosis, lymphoproliferation, and a lupus-like autoimmune disease associated with the production of autoantibodies. Other than Fas pathway defects, little is known about molecular abnormalities that predispose to autoimmunity. Protein kinase CK2 (also termed casein kinase II), a serine-threonine protein kinase whose targets include many critical regulators of cellular growth, is highly expressed in a lymphoproliferative disease of cattle and in many human cancers. Overexpression of the CK2α catalytic subunit in lymphocytes of transgenic mice leads to T cell lymphoma. We hypothesized that CK2 dysregulation and Fas mutation might cooperatively augment lymphocyte proliferation and transformation. We find that in MRL-lpr/lpr mice bearing the CK2α transgene, the lymphoproliferative process is dramatically exacerbated, as these mice develop massive splenomegaly and lymphadenopathy by 12 wk of age in association with increased autoantibody production and accelerated renal disease. The lymphoid organs are filled with the unusual B220+CD4−CD8− T cells typically seen in MRL-lpr/lpr mice, not the B220−CD4+CD8+ or B220−CD4−CD8+ T cells typically seen in CK2α transgenic lymphomas. The T cells do not fulfill the criteria for transformation, as they are polyclonal and not transplantable or immortal in cell culture. Thus, although the lpr lymphoproliferative and autoimmune syndrome is potentiated by the presence of the CK2α transgene, this combination of apoptotic and proliferative abnormalities appears to be insufficient to transform lymphoid cells.

T-cell receptor Vbeta gene expression in experimental lupus nephritis

A limited T-cell receptor (TCR) Vbeta repertoire employed by autoreactive T cells may be related to the development and course of autoimmune diseases. Vbeta repertoire skewing has been observed not only in man, but also in animal models of several human autoimmune diseases, such as MRL-lpr mice, which spontaneously develop a systemic lupus erythematosus (SLE)-like disease. Murine chronic graft-versus-host disease (GVHD) is an inducible model for SLE, involving direct interaction between donor T cells and recipient B cells. It is not known whether Vbeta-specific T-cell subsets are pathogenically involved in this model. Retroviral superantigens such as Mls-1 are known to have a profound impact on the TCR Vbeta repertoire in mice. Restriction of the peripheral TCR repertoire may result from intrathymic expression of Mls-1, which causes deletion of T cells expressing Vbeta6, -7, -8.1, or -9. Mls-1 incompatibility between donor and recipient can be used to determine the involvement of these TCR Vbeta families in GVHD. In the present study we induced GVHD in several strain combinations to investigate TCR Vbeta gene expression during GVHD, and the effect of Mls-1 incompatibility on the TCR Vbeta repertoire. TCR Vbeta gene expression was determined using an RNase protection assay. Our results indicate that T cells expressing the Vbeta2 or Vbeta16 chain play an important pathogenetic role, while T cells bearing the Vbeta1 or Vbeta6 chain may be related to self-limitation of the lupus-like disease in this model.

Anti-T-cell receptor therapy in murine experimental systemic lupus erythematosus

Experimental systemic lupus erythematosus (SLE), similar to that observed after immunization with the human anti-DNA mAb 16/6 Id+, could be induced in mice by injection of 16/6 Id specific T-cell lines. The above T-cell lines were exclusively CD4+ CD8- and the majority of cells expressed the Vbeta8 T-cell receptor (TCR) gene products. Furthermore, lymph node cells of mice immunized with the 16/6 Id were enriched with CD4+ Vbeta8+ T-cells. The TCR used by 16/6 Id-specific T-cells showed a limited homology in their CDR3 junctional regions. Nevertheless, mice injected with the anti-Vbeta8 mAb developed autoantibody titers that were not significantly different from those found in the non-treated, 16/6 Id-injected group.

Analysis of Vbeta4 T cell receptor CDR3 repertoire in BALB/c and (NZB x NZW)F1 mice

To examine the unique TCR repertoire in auto-immune-prone (NZB x NZW)F1 (B/WF1) mice, we analysed the Vbeta4 CDR3 region of TCRbeta chain in spleens of young (1 month old) and aged (6 month old) BALB/c and B/WF1 mice. Total RNA from spleens was used for cDNA synthesis and TCRVbeta4 PCR products were cloned and sequenced. Young B/WF1 mice showed high frequency (38.5%) of anionic amino acid residues at position beta100 in TCRVbeta4 chain compared to that (19.0%) in young BALB/c mice. Aged BALB/c mice and B/WF1 mice showed increase of frequency (38.1 and 51.9%, respectively) of anionic residues at beta100. These results indicate that Vbeta4-T cells that have anionic residues at beta100 in CDR3 region of TCRbeta chain increase with age in normal mice. Auto-immune prone mice show high frequency of anionic residues at beta100 in TCRVbeta4 chain even at the age of 1 month. These T cells may interact with cationic self-antigen(s) and might contribute to the onset and/or the progression of systemic autoimmunity in concert with other genetic elements in B/WF1 mice.

Matrix and adhesion molecules in kidney pathology: recent observations

The purpose of this article is to review a set of recently obtained data concerning matrix and matrix adhesion molecules in renal disease. Our goal is not to cover the entire topic, but rather to focus on findings obtained with an experimental model for chronic lupus nephritis, evoked in mice by inducing graft-versus-host disease (GVHD). The overall aim of these studies was to investigate the role of adhesion molecules as targets for autoantibodies, in the recruitment of inflammatory cells, and in the accumulation of matrix in kidney disorders. In addition, we set out to discover how matrix proteins in renal diseases differ from normal matrix molecules both quantitatively, in their increased frequency, and qualitatively, in their intramolecular structure. The advances in understanding and methodology described in this review imply a substantial capability for greater insight into the pathogenesis of kidney disease; for making better use of renal biopsies, such as in applying competitive reverse-transcriptase-polymerase chain reaction (RT-PCR) in RNA analysis for matrix; and in developing more effective treatment strategies for patients with kidney disease.

Immunobiology and immunotherapeutic implications of syngeneic/autologous graft-versus-host disease

Administration of the immunosuppressive drug cyclosporine (CsA) after syngeneic/autologous bone marrow transplantation (BMT) elicits an autoimmune syndrome with pathology virtually identical to graft-vs-host disease (GVHD). The induction of this syndrome, termed syngeneic/autologous GVHD, is a two-tiered process requiring both the active inhibition of thymic-dependent clonal deletion and the elimination of mature T cells that have an immunoregulatory effect. Eradication of the peripheral immunoregulatory compartment by the preparative regimen provides a permissive environment for the activation of the syngeneic/autologous GVHD effector T cells. Although the repertoire of autoreactive effector T lymphocytes is highly conserved, these T cells promiscuously recognize MHC class II determinants. This novel specificity of the autoreactive lymphocytes appears to be dependent on the peptide derived from the MHC class II invariant chain. Recent studies also suggest that these promiscuous autoreactive T cells can effectively target and eliminate MHC class II-expressing tumor cells. Administration of cytokines that upregulate the target antigen or expand the effector population can potentiate the antitumor activity of syngeneic/autologous GVHD. Although the induction of syngeneic/autologous GVHD is an untoward effect of CsA immunosuppression, mobilization of these autoimmune mechanisms provides a promising immunotherapeutic approach for certain neoplastic diseases.

Breakdown of B cell tolerance in a mouse model of systemic lupus erythematosus

Anti-DNA antibodies, specifically those that stain nuclei in a homogenous nuclear (HN) fashion, are diagnostic of systemic lupus erythematosus (SLE) and the MRL-lpr/lpr SLE murine model. We have used a heavy chain transgene that increases the frequency of anti-HN antibodies to address whether their production in SLE is the consequence of a defect in B cell tolerance. Anti-HN B cells were undetectable in nonautoimmune-prone transgenic mice, but in MRL-lpr/lpr transgenic mice their Ig was evident in the sera and they were readily retrievable as hybridomas. We conclude that nonautoimmune animals actively delete anti-HN-specific B cells, and that MRL-lpr/lpr mice are defective in this process possibly because of the lpr defect in the fas gene.

The basis of autoimmunity: Part I. Mechanisms of aberrant self-recognition

In this two-part series, Argyrios N. Theofilopoulos summarizes the current state of affairs in the field of autoimmunity. Part I integrates the collective mechanistic theories of autoimmune diseases. The most straightforward explanation to emerge with regard to organ-specific diseases is the concept that these are caused by inappropriate, yet conventional, immunological responses against self-antigens for which tolerance has never been established. A similar mechanism may be operative in systemic autoimmunity, but other abnormalities such as defects in the apoptosis machinery may also be invoked. Part II will address the genetic contributions predisposing to autoimmune syndromes.

V beta gene repertoire in the aging mouse: a developmental perspective

To define age-associated alterations in the immune system at the molecular level, we have analyzed TCR V beta gene expression patterns at the fetal, neonatal, adult, and advanced ages of mice. In contrast to V gamma and VH genes, V beta genes rearranged without any preference related to their chromosomal organization. Endogenous superantigen-mediated clonal deletions were registered for the first time at the neonatal stage, presumably reflecting the late developmental appearance of these molecules. Such deletions, once established, were maintained throughout life with little, if any, leakage in this process. Furthermore, bone marrow transplantation and other studies indicated that an involuted thymus maintained its capacity to perform both its functions, i.e. positive and negative selection. Although overall V beta repertoires showed remarkable stability with advanced age, modifications in expression levels for some V beta, particularly those associated with the CD8 subset and presumably reflecting antigenic stimulation, were recorded. Mice with lupus and early-life thymic involution were fully capable of deleting endogenous superantigen-reactive V beta clones, and even lupus mice with a genetic defect in the apoptosis-promoting Fas gene were normal in this regard. The results indicate that, aside from some anticipated clonal expansions induced by antigenic stimulation, age-associated alterations in immune functions are not caused by any profound changes in the overall TCR repertoire.

Anchored polymerase chain reaction based analysis of the V beta repertoire in the non-obese diabetic (NOD) mouse

We have performed extensive analyses of T cell receptor V beta usage in the thymus, the spleen and the infiltrated islets of preclinical non-obese diabetic (NOD) mice. A semiquantitative anchored polymerase chain reaction (An-PCR) protocol has been developed for this purpose. The validity of the method has been first assessed by antibody staining with a panel of anti-V beta monoclonal antibodies (mAb). The results obtained by An-PCR are accurate, reproducible, and in good agreement with cell surface protein staining. A strict comparison between thymus and spleen repertoires reveals no major V beta-specific deletion except the already reported V beta 3 deletion due to Mtv-3. Certain V beta such as V beta 15, 18, 20 are found with a low frequency in the spleen, but the fact that they are also scarce in the thymus probably reflects a poor availability of these genetic elements during beta chain rearrangement rather than negative selection. Other V beta, such as V beta 2, V beta 12 and V beta 14 are significantly more abundant in the spleen than in the thymus. This finding was confirmed by mAb staining for V beta 2 and V beta 14. The expansion asymmetrically affects the CD4+ subset and can be traced back to the mature, single-positive thymocyte subset, suggesting an intrathymic positive selection event. V beta repertoires in infiltrated islets of 13- and 18-week-old, non-diabetic mice are polymorphic. Practically all the V beta found in the peripheral lymphoid tissues are present in the islets, in similar proportions. The major exception is V beta 12, one of the V beta which is subject to expansion during intrathymic differentiation and which is further augmented in the islets, both at 13 and 18 weeks. This increase probably reflects further peripheral amplification of the V beta 12-bearing subset due to encounter with the same ligand as in the thymus or with a cross-reactive motif. Finally, the nucleotide sequencing of all the V beta segments in usage in the NOD strain confirms the absence of allelic polymorphism of V beta-coding regions.

Attenuation of lpr-graft-versus-host disease (GVHD) in MRL/lpr spleen cell-injected SCID mice by in vivo treatment with anti-V beta 8.1,2 monoclonal antibody

When MRL/lpr (H-2k) spleen cells were intraperitoneally injected into C.B-17-scid/scid (severe combined immunodeficient (SCID)) (H-2d) mice, the SCID (SCID-MRL/lpr) mice manifested a severe wasting syndrome with weight loss, splenic atrophy, and lymphoid cell infiltration in the liver and lung, as seen in lpr-GVHD. In contrast, MRL/+ spleen cell-injected SCID (SCID-MRL/+) mice did not show lpr-GVHD. The spleens of SCID-MRL/lpr mice showed progressive increases in donor CD4+ and CD8+ T cells from 4 to 12 weeks after injection and a decrease in B cells at 12 weeks. SCID-MRL/+ mice showed a stable engraftment of CD4+ and CD8+ T cells and a progressive increase in B cells. Analyses of T cell receptor (TCR) repertoires (V beta 6, V beta 8.1,2 and V beta 11) revealed that the V beta 8.1,2+ T cells were found more frequently in SCID-MRL/lpr mice than in SCID-MRL/+ mice. When SCID-MRL/lpr mice were treated with intraperitoneal injection of an anti-V beta 8.1,2 (KJ16) MoAb, V beta 8.1,2+ T cells were markedly depleted, and the severity of lpr-GVHD was attenuated at 4 and 8 weeks after treatment, in contrast to normal rat IgG-injected SCID-MRL/lpr mice. However, the KJ16 MoAb-treated SCID-MRL/lpr mice suffered from severe lpr-GVHD 12 weeks after treatment, although V beta 8.1,2+ T cells were still maintained at a low level. These findings suggest that V beta 8.1,2+ T cells are a major T cell population that mediates lpr-GVHD in the early stage of lpr-GVHD, but that in the later stage, the other T cell populations may proliferate naturally or in accordance with the depletion of V beta 8.1,2+ T cells, and contribute to the development of lpr-GVHD.

V beta gene repertoires in T cells expanded in local self-healing and lethal systemic murine cutaneous leishmaniasis

Inbred mice infected with Leishmania major promastigotes display two different courses of leishmaniasis: resistant strains develop self-healing local sores, while susceptible strains show progressive systemic disease with lethal outcome. Resistance predominantly correlates with the production of T helper type 1 (TH1) lymphokines and susceptibility with production of TH2-type lymphokines. Here, we analyzed whether this TH phenotype difference correlates with expression of particular T cell receptor V beta chains. Our results show that T cells expand strongly during infection in all groups of mice and invariantly express the same V beta gene families as prior to infection. Our data indicate that TH1 and TH2 cells use similar V beta gene families, and argue against the engagement of a restricted set of V beta by dominant determinants associated with L. major.

Beneficial effect of polyclonal immunoglobulins from malaria-infected BALB/c mice on the lupus-like syndrome of (NZB x NZW)F1 mice

We previously reported that infection of BALB/c mice with the parasite Plasmodium chabaudi induces high production of natural autoantibodies. Here we demonstrate that such an infection of lupus-prone (NZB x NZW)F1 (B/W) mice retards the development of their autoimmune disease. Survival and disease hallmarks (high-grade proteinuria and IgG anti-DNA antibodies) were delayed for 6 months when parasite inoculation was given at either 3 or 7 months of age, i.e. before or after the onset of the clinical symptoms. Similar beneficial effects, although less pronounced, were obtained when mice were treated with a total of 800 micrograms of IgG (P-IgG) or IgM (P-IgM) or 300 micrograms of cryoglobulin preparations isolated from P. chabaudi-infected BALB/c mice while similarly prepared fractions from uninfected mice had little effect. Compared to these fractions, P-IgG and P-IgM contained higher levels of natural antibodies bearing the D23 idiotype characteristic of polyreactive natural autoantibodies with enhanced activity against Fab and Fc fragments of IgG. In surviving mice, the level of anti-DNA antibodies, particularly those of IgG1 isotype, were significantly decreased. Flow cytometric analysis of various T cell subsets showed that the number of cells expressing gamma delta T cell receptor (TcR) antigens which did not vary with age was not modified after P-IgG or P-IgM treatment. In contrast, the number of T cells expressing V beta 8.1,2,V beta 10 and V beta 14 TcR antigens, which increased with age, were significantly reduced. Taken together, these results indicate that parasite infection of mice induces the synthesis of populations of IgM and IgG natural autoantibodies with immunoregulatory properties and that these antibodies attempt, at least transitorily, to rescue a natural autoantibody network that is deficient in B/W mice.

Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.

T-cell receptor genes in autoimmunity

T cells are primary participants in the pathogenesis of the MHC-dependent autoimmune diseases, and therefore, evidence for association of TCR V-gene repertoires with such disorders has been actively sought. With very few exceptions, no clear-cut evidence for correlation of particular RFLP-defined V-C-region genomic polymorphisms with autoimmune disease predisposition has thus far been demonstrated. With regard to TCR V-gene repertoires engaged in responses to autoantigens, restricted use of certain V beta and V alpha genes in response to myelin basic protein has been documented in animal models. In many spontaneous and experimentally induced animal and human autoimmune diseases, however, the picture is far from clear. Although dominance of certain TCR V genes has been noted, the clonal restrictions are not absolute; they differ from one study to another and from one patient to another. Such variations may be caused by MHC allele-dependent determinant selection mechanisms, secondary T-cell infiltrates in inflammatory sites, different patient populations and stages of disease, or the involvement of different pathogens that, nevertheless, lead to the same clinical entity. Overall, the results indicate that efforts to intervene therapeutically in autoimmune diseases by vaccination with modified T-cell clones, V region-synthetic peptides, or TCR blocking analogues may not be easily applicable. Further studies on the characterization of the specific antigens involved in autoimmune disease pathogenesis is required in order to accurately address the issue of TCR utilization in autoimmune diseases.

The IE allogeneic response of T cells from C57Bl/6 mice is associated with genes in the TCRa locus

It has been demonstrated that induction of immune responses, infectious diseases and autoimmune manifestations can be associated with at least four gene loci: the major histocompatibility complex (MHC) locus; the immunoglobulin (Ig) heavy chain (Hc) locus; and the T-cell receptor (TCR) TCR-alpha or TCR-beta chain loci. In the present study, we have analysed whether T-cell responses of IE-negative C57Bl/6 (B6) mice to IE alloantigen (IE alpha transgenic B6 mice = B6.E alpha 16) or to trinitrophenylated (TNP) syngeneic spleen cells were influenced by changes in the Ig-Hc locus or the TCRa locus. Whereas the fine specificity of T-cell responses to IE alloantigen was the same in B6 mice and in Ig-Hc congenic B6.26a or TCRa congenic B6.10TCa mice, the latter strain of mice demonstrated much higher IE-specific T-cell responses against B6.E alpha 16 spleen cells than B6 or B6.26a mice. This high responsiveness was a dominant feature and associated with the TCRa locus. In addition, the TCRV alpha or V beta repertoire of the congenic strains of mice was polyclonal and very similar. The TNP-specific T-cell responses of B6 and B6.10TCa mice showed the same restricted TCRV alpha and V beta repertoire. It is concluded that in both an oligoclonal T-cell response (anti-TNP) and a polyclonal T-cell response (anti-IE), exchange of Ig-Hc or TCRa loci does not significantly influence the TCRV alpha or V beta repertoire in IE-negative C57Bl/6 mice.

Compartmentalization of the peripheral immune system

The periphery of the immune system--as opposed to the central lymphoid organs--contains inhomogeneously distributed B and T cells whose phenotype, repertoire, developmental origin, and function are highly divergent. Nonconventional lymphocytes bearing a phenotype that is rare in the blood, spleen, or lymph nodes of undiseased individuals are encountered at high frequency in different localizations, e.g., alpha/beta TCR+CD4-CD8- cells in the bone marrow and gut epithelium, particular invariant gamma/delta TCR+CD4-CD8 alpha+CD8 beta- and gamma/delta TCR+CD4-CD8 alpha-CD8 beta- T cells in various epithelia, or CD5+ B cells in the peritoneum. The antigen receptor repertoire is different in each localization. Thus, different gamma/delta TCR gene products dominant in each site, and the proportion of cells expressing transgenic and endogenous alpha/beta TCR and immunoglobulin gene products follows a gradient, with a maximum of endogenous gene expression in the peritoneum, intermediate values in other peripheral lymphoid organs (spleen, lymph nodes), and minimum values in thymus and bone marrow. Forbidden T cells that bear self-superantigen-reactive V beta gene products are physiologically detected among alpha/beta TCR+CD4-CD8- lymphocytes of the bone marrow, as well as in the gut. Violating previous ideas on self-tolerance preservation, self-peptide-specific gamma/delta T cells are present among intestinal intraepithelial lymphocytes, and CD5+ B cells produce low-affinity crossreactive autoantibodies in a physiological fashion. It appears that, in contrast to the bulk of T and B lymphocytes, certain gamma/delta and alpha/beta T cells found in the periphery, as well as most CD5+ B cells, do not depend on the thymus or bone marrow for their development, respectively, but arise from different, nonconventional lineages. In addition to divergent lineages that are targeted to different organs guided by a spatiotemporal sequence of tissue-specific homing receptors, local induction or selection processes may be important in the diversification of peripheral lymphocyte compartments. Selection may be exerted by local antigens, antigen-presenting cells whose function varies in each anatomical localization, cytokines, and cell-matrix interactions, thus leading to the expansion and maintenance of some clones, whereas others are diluted out or deleted. The spatial compartmentalization of lymphocytes in different microenvironments has major functional consequences and leads to a partial fragmentation of immunoregulatory circuits at the local level. Lymphocytes residing in certain antigen-exposed compartments are likely to combat tissue-specific pathogens or self-proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Dissociation of autoaggression and self-superantigen reactivity

Self-superantigens have been described as products of endogenous retroviruses of the mouse ('minor lymphocyte stimulating loci') that are capable of interacting without prior processing with conserved domains of TCR V beta chains, causing the activation and deletion of most T cells expressing products of determined V beta gene families [1-4]. The fact that superantigens activate a far higher percentage of T cells (1-20%) than conventional, peptidic antigens (< 0.1%) provides the methodological advantage that the degree of clonal deletion may be measured by the analysis of the TCR repertoire using appropriate anti-V beta antibodies. Although much information on the spatio-temporal organization of repertoire-purging has been gathered by virtue of self-superantigens, serious doubts exist as to the possibility that such structures serve as pathogenetically relevant autoantigens. Thus, certain inbred mice spontaneously develop autoimmune diseases, although they bear T-cell repertoires that appear to be purged from self-superantigen-reactive V beta products. In addition, therapeutic interventions targeted to V beta gene products that are not specific for self-superantigens are successful in preventing disease development. The lack of correlation between superantigen-related V beta deletions and autoimmune disease development is substantiated in further models of murine autoimmunity. Based on these observations, we formulate the hypothesis that self-superantigen-reactive T cells are not involved in the development of autoimmune diseases.

Attenuation of autoimmune disease and lymphocyte accumulation in MRL/lpr mice by treatment with anti-V beta 8 antibodies

MRL-MP-lpr/lpr mice are afflicted by a severe systemic autoimmune disease that is aggravated by the lpr mutation resulting in the accumulation of phenotypically abnormal lpr cells (CD3+CD4-CD8-) in all lymphoid issues including hyperplastic lymph nodes. Given that products of the T cell receptor V beta 8 gene family are overrepresented among lpr cells, different schedules aimed at selectively decreasing the frequency of lpr cells were designed. First, continuous administration of the monoclonal antibody F23.1 (specific for V beta 8 products) resulted in a significant depletion of V beta 8+ cells and prevented the manifestation of lymph accumulation at the same time as it reduced the serological, clinical, and histopathological signs of autoimmune disease. Along the same line, administration of either F23.1 or two different anti-F23.1 anti-idiotypic antibodies to MRL/Mp-lpr/lpr mothers elicited, in the offspring, the production of antibodies sharing a recurrent idiotype with F23.1 and resulted in long-term amelioration of autoimmunity and lymphadenopathy. Thus, a strategy aimed at specifically reducing the frequency of a subset of lpr cells proved successful in mitigating the autoimmune process.

Genetic regulation of CD5+ B cells in autoimmune disease and in chronic lymphocytic leukemia

CD5+ B cells have attracted much attention, because of their involvement in both autoimmunity and B cell-type chronic lymphocytic leukemia (B-CLL). B-CLL is a type of leukemia most often occurring among close relatives and is partly associated with the major histocompatibility complex (MHC), a finding relevant to autoimmune disease. We established MHC (H-2)-congenic NZB x NZW (NZB/W) F1 mice (H-2d/z, H-2z/z, and H-2d/d), in that only H-2d/z heterozygotes developed severe SLE, associated with IgG anti-DNA antibodies, as the animals aged. Such age-associated changes occurred in parallel with the decrease in the splenic, but not peritoneal, CD5+ B cells. By contrast, H-2z/z homozygotes did not develop SLE but, in turn, a marked clonal proliferation of CD5+ B cells resembling B-CLL did occur. H-2d/d homozygotes also did not develop the typical SLE, and a moderate CD5+ B frequency persisted. Despite the finding that all the three H-2-congenic NZB/W F1 strains produced IgM anti-DNA antibodies, only the H-2d/z heterozygotes produced IgG antibodies. Whereas the surface phenotype of major IgM producers was CD5+ sIgM+, that of IgG producers was CD5-sIgM-. Genetic and cellular analyses supported our thesis that in the heterozygotes IgM to IgG isotype switching probably emerges in CD5+ B cells and that this event is associated with the loss of CD5 molecules. Because of the lack of genetic elements required for differentiation, only signals for proliferation would be functioning in CD5+ B cells in the H-2z/z homozygotes. These observations infer that certain different, but related, MHC haplotypes may predispose either to B-CLL or to autoimmune disease in close relatives.

lpr T cells vaccinate against lupus in MRL/lpr mice

MRL/MP-lpr/lpr mice are homozygous for the lpr mutation that results in the accumulation of phenotypically abnormal cells (CD3+CD4+CD8-) in all lymphoid issues. Although no major abnormalities in the T cell receptor repertoire expressed by such lpr cells have been reported, the lpr mutation is a major disease-accelerating factor. Finally, intravenous administration of irradiated lpr cells recovered from the hyperplastic lymph nodes of adult diseased animals to young MRL/Mp-lpr/lpr mice resulted in a highly significant amelioration of disease parameters. This "T cell vaccination" approach resulted in a selective depletion of cells expressing products of the V beta 8.2 subfamily among lymph node T cells, in addition to eliciting a surge in peripheral T cells capable of conferring disease protection in adoptive transfer experiments. Thus, a strategy aimed at specifically reducing the frequency of lpr cells proved successful in mitigating the autoimmune process. These findings add to the involvement of lpr cells in the autoimmune process and constitute the first report that T cell vaccination may be beneficial to a spontaneously occurring autoimmune disease.

Genetic association between natural autoantibody responses to histones and DNA in murine lupus

Genetic regulation of the spontaneous anti-histone antibody production in systemic lupus erythematosus (SLE) was studied using the H-2-congenic and T cell receptor beta chain gene complex (TCR beta)-congenic NZB and NZW strains and their crosses. We found that the original, parental H-2d/d NZB mice produced significantly higher titers of serum IgM class anti-histone antibodies than did the congenic H-2d/z or H-2z/z NZB mice. However, none of these three NZB strains produced IgG antibodies. The NZW strain of any H-2 haplotype did not produce IgM and IgG anti-histone antibodies. The IgG anti-histone antibodies were produced only by H-2d/z heterozygous NZB x NZW F1, but not by homozygous H-2z/z or H-2d/d NZB x NZW F1 mice. In studies using (NZB x NZW) F1 x NZB backcross mice, only the progeny having both H-2d/z and NZW-type TCR beta genotypes produced high amounts of IgG antibodies. There was a tight linkage between the NZW-type TCR beta and the production of IgG anti-histone antibodies in TCR beta-congenic NZB x NZW F1 mice. All these findings were in keeping with our preceding observations on the genetic regulation of anti-DNA antibodies in these mice and suggest that certain common mechanisms such as super-antigen-mediated or common idiotope-mediated regulations may underlie the production of these two distinct autoantibodies in NZB x NZW F1 mice.

Reduction of lupus nephritis in MRL/lpr mice by a bacterial superantigen treatment

The effects of biweekly intravenous injections of Staphylococcus Enterotoxin B (SEB) into autoimmune MRL-lpr/lpr (MRL/lpr) mice were investigated. Rather than causing the expansion of V beta 8+ T cells, SEB administration resulted in the reduction V beta 8+, CD4-CD8- "double-negative" (DN) T cells. This was shown by FACS analysis as this putative pathogenic population was diminished in both spleen and lymph node. The symptoms of systemic lupus erythematosus (SLE) in MRL/lpr, which include high titers of anti-DNA antibodies and circulating immune complexes and proteinuria, were reduced in SEB-treated mice in a dose-dependent manner. The clinical parameters of SLE in MRL/lpr, which include lymph node hyperplasia and necrotic vasculitis, were suppressed in 50-micrograms SEB-treated mice. T cells bearing V beta 6 T cell receptor, which does not interact with SEB, were not reduced with SEB administration. Thus, disease suppression was associated with a specific reduction in the number of V beta 8+, DN T cells. These results implicate a possible therapeutic role of superantigen-based immunotherapy in V beta-restricted, T cell-dominated clinical syndromes.