Limiting dilution analysis of proliferative T cell responses to mycobacterial 65-kDa heat-shock protein fails to show significant frequency differences between synovial fluid and peripheral blood of patients with rheumatoid arthritis

Anti-inflammatory or proinflammatory effect of an adenosine receptor agonist on the Th17 autoimmune response is inflammatory environment-dependent

Adenosine is a key endogenous signaling molecule that regulates a wide range of physiological functions, including immune system function and inflammation. Studies have shown that adenosine receptor (AR) agonists can be either anti-inflammatory or proinflammatory in immune responses and in inflammation, and the clarification of the mechanisms causing these opposing effects should provide a better guide for therapeutic intervention. Whereas previous studies mostly examined the effects of AR agonists on Th1-type immune responses, in this study, we compared their effect on Th17 and Th1 autoimmune responses in experimental autoimmune uveitis, a mouse model of human uveitis induced by immunization with the human interphotoreceptor retinoid-binding protein peptides 1-20. We showed that injection of mice with a nonselective AR agonist, 5'-N-ethylcarboxamidoadenosine (NECA), at an early stage after immunization had an inhibitory effect on both Th1 and Th17 responses, whereas injection of the same amount of NECA at a late stage inhibited the Th1 response but had an enhancing effect on the Th17 response. We also showed that the effects of NECA on Th1 and Th17 responses were completely dissociated, that the enhancing effect of NECA on Th17 responses was modulated by γδ T cells, and that the response of γδ T cells to NECA was determined by their activation status. We conclude that the inflammatory environment has a strong impact on converting the effect of AR agonist on the Th17 autoimmune response from anti-inflammatory to proinflammatory. Our observation should help in the designing of better AR-targeted therapies.

Cord blood CD4+ T cells respond to self heat shock protein 60 (HSP60)

Background

To prevent harmful autoimmunity most immune responses to self proteins are controlled by central and peripheral tolerance. T cells specific for a limited set of self-proteins such as human heat shock protein 60 (HSP60) may contribute to peripheral tolerance. It is not known whether HSP60-specific T cells are present at birth and thus may play a role in neonatal tolerance. We studied whether self-HSP60 reactive T cells are present in cord blood, and if so, what phenotype these cells have.

Methodology/Principal Findings

Cord blood mononuclear cells (CBMC) of healthy, full term neonates (n = 21), were cultured with HSP60 and Tetanus Toxoid (TT) to study antigen specific proliferation, cytokine secretion and up-regulation of surface markers. The functional capacity of HSP60-induced T cells was determined with in vitro suppression assays. Stimulation of CBMC with HSP60 led to CD4⁺ T cell proliferation and the production of various cytokines, most notably IL-10, Interferon-gamma, and IL-6. HSP60-induced T cells expressed FOXP3 and suppressed effector T cell responses in vitro.

Conclusion

Self-reactive HSP60 specific T cells are already present at birth. Upon stimulation with self-HSP60 these cells proliferate, produce cytokines and express FOXP3. These cells function as suppressor cells in vitro and thus they may be involved in the regulation of neonatal immune responses.

The involvement of heat-shock proteins in the pathogenesis of autoimmune arthritis: a critical appraisal

OBJECTIVES

To review the literature on the role of heat-shock proteins (HSPs) in the pathogenesis of autoimmune arthritis in animal models and patients with rheumatoid arthritis (RA).

METHODS

The published literature in Medline (PubMed), including our published work on the cell-mediated as well as humoral immune response to various HSPs, was reviewed. Studies in the preclinical animal models of arthritis as well as RA were examined critically and the data are presented.

RESULTS

In experimental arthritis, disease induction by different arthritogenic stimuli, including an adjuvant, led to immune response to mycobacterial HSP65 (BHSP65). However, attempts to induce arthritis by a purified HSP have not met with success. There are several reports of a significant immune response to HSP65 in RA patients. However, the issue of cause and effect is difficult to address. Nevertheless, several studies in animal models and a couple of clinical trials in RA patients have shown the beneficial effect of HSPs against autoimmune arthritis.

CONCLUSIONS

There is a clear association between immune response to HSPs, particularly HSP65, and the initiation and propagation of autoimmune arthritis in experimental models. The correlation is relatively less convincing in RA patients. In both cases, the ability of HSPs to modulate arthritis offers support, albeit an indirect one, for the involvement of these antigens in the disease process.

The human endoplasmic reticulum molecular chaperone BiP is an autoantigen for rheumatoid arthritis and prevents the induction of experimental arthritis

Rheumatoid arthritis (RA) is the most common, crippling human autoimmune disease. Using Western blotting and tandem mass spectroscopy, we have identified the endoplasmic reticulum chaperone BiP, a 78-kDa glucose-regulated protein, as a possible autoantigen. It preferentially stimulated increased proliferation of synovial T cells from patients with RA but not from patients with other arthritides. Mice with established collagen- or pristane-induced arthritis developed IgG Abs to BiP. Although BiP injected in CFA failed to induce arthritis in several strains of rats and mice, including HLA-DR4(+/-)- and HLA-DR1(+/+)-transgenic animals, it completely inhibited the development of arthritis when given i.v. 1 wk before the injection of type II collagen arthritis. Preimmunization with BiP suppressed the development of adjuvant arthritis in Lewis rats in a similar manner. This is the first report of a mammalian chaperone that is an autoantigen in human RA and in experimental arthritis and that can also prevent the induction of experimental arthritis. These findings may stimulate the development of new immunotherapies for the treatment of RA.

Tracking antigen-specific human T lymphocytes in rheumatoid arthritis by T cell receptor analysis

The aim of this study was to use TCR sequencing as a tool to address the frequency of antigen specific T cells in different T cell compartments from a rheumatoid arthritis patient. We have previously established a clear link between T cell recognition of a specific Mhsp60 epitope and the amino acid sequence in the CDR3 region of the TCRB chain. This information was used to determine the frequency of these characteristic sequences in unmanipulated synovial fluid (SF), peripheral blood (PB) and hyperplastic lymph node of the same patient by amplification and sequencing. TCRBV sequences identical to those seen in antigen-specific clones, and closely related sequences, were readily identified in SF, where they represented approximately 1% of all T cells, but were absent from PB or lymph node. The prevalence of putative Mhsp60 specific T cells within the SFMC is much greater than previously suggested by limiting dilution assays. Thus, amplification and sequencing may prove a superior technique for tracking the frequency of antigen-specific T cells in different tissues and in a longitudinal fashion.

HLA-DRB1 motifs and heat shock proteins in rheumatoid arthritis

Susceptibility to develop Rheumatoid arthritis (RA) maps to a highly conserved amino acid motif expressed in the third hypervariable region of different HLA-DRB1 alleles. This motif, namely QKRAA, QRRAA or RRRAA helps the development of RA by an unknown mechanism. In the past ten years, we have extensively studied the unique properties of the QKRAA motif of HLA-DRB1*0401 and have found: (1) That it can constitute B and T cell epitopes on many infectious agents; (2) That it can shape the T cell repertoire; (3) That it is overrepresented in protein databases; (4) That it constitutes a binding motif for the highly conserved family of 70 kD heat shock proteins. This may cause abnormal trafficking of HLA-DRB1*0401 in B cells and/or abnormal T cell responses to bacterial and human 70 kD heat shock proteins in people who express HLA-DRB1*0401.

Role of heat shock proteins in protection from and pathogenesis of infectious diseases

Increased synthesis of heat shock proteins (hsp) occurs in prokaryotic and eukaryotic cells when they are exposed to stress. By increasing their hsp content, cells protect themselves from lethal assaults, primarily because hsp interfere with the uncontrolled protein unfolding that occurs under stress. However, hsp are not produced only by stressed cells; some hsp are synthesized constitutively and perform important housekeeping functions. Accordingly, hsp are involved in the assembly of molecules which play important roles in the immune system. It is not surprising that due to their wide distribution and their homology among different species, hsp represent target antigens of the immune response. Frequent confrontation of the immune system with conserved regions of hsp which are shared by various microbial pathogens can potentiate antimicrobial immunity. However, long-term confrontation of the immune system with hsp antigens which are similar in the host and invaders may convert the immune response against these host antigens and promote autoimmune disease. This review provides an overview of the role of hsp in immunity with a focus on infectious and autoimmune diseases.

Heat shock proteins and arthritis--new readers start here

The possible roles of heat shock proteins in the pathogenesis of inflammatory arthritis have been discussed for a number of years, and investigated intensively in both animal models and human disease. This review surveys evidence which has pointed, on the one hand, to hsp as targets of a pathogenic immune response, and on the other, to an immunoregulatory role for T cell recognition of self hsp. The extent to which findings in experimental animals have led to further insights applicable to human disease is also emphasised.

The role of regulatory T cells in Lewis rats resistant to EAE

Adult Lewis (LEW) rats are highly susceptible to experimental autoimmune encephalomyelitis (EAE), induced actively by immunization with guinea pig (GP) myelin basic protein (MBP) in complete Freund's adjuvant or adoptively transferred with activated T lymphocytes reactive to GP MBP peptide 68-88. Once LEW rats recover from active EAE or when given MBP in incomplete Freund's adjuvant (IFA), they become resistant to further attempts to induce active or passive EAE. In this study, we examined whether such EAE-resistant rats after MBP-IFA immunization have reduced frequencies of MBP-reactive T cells, whether these T cells are anergized, and whether the activity of regulatory T cells is increased to the event that they prevent activation of MBP-specific T cell subpopulations. By limiting dilution analyses (LDA) of unfractionated splenic T cells, the levels of MBP-reactive T cells in EAE-resistant rats appeared to be approximately 5% of the levels in EAE-susceptible rats. However, a subsequent analysis of CD4+ enriched T cell populations, depleted of the CD8 subset, showed similar frequencies of MBP-reactive cells in susceptible and resistant LEW rats. Not only were the frequencies on LDA altered by suppressor cells, but also LDA comparisons based on cell proliferation and cytokine production as indicators of MBP reactive cell frequencies gave markedly different results. We conclude that MBP-reactive T cells in this model of EAE-resistant LEW rats are hyporeactive to MBP as the result of an increased activity of a regulatory subset of CD8+ T cells. These results also demonstrate that the quantitation of MBP-reactive CD4+ T cells by LDA is strongly influenced by the presence of functionally antagonistic CD8+ T cells, which cause an underestimation of responder T cell frequencies, and by the method of detecting T cell reactivity.

Clonal expansion of mycobacterial heat-shock protein-reactive T lymphocytes in the synovial fluid and blood of rheumatoid arthritis patients

OBJECTIVE

To examine the reactivity pattern and T cell receptor (TCR) characteristics of mycobacterial heat-shock protein 65 (hsp65)-reactive T cells generated from paired synovial fluid (SF) and peripheral blood (PB) samples obtained from rheumatoid arthritis (RA) patients and from healthy subjects.

METHODS

The reactivity pattern of hsp65-reactive T cell clones generated under limiting-dilution conditions was analyzed in 3H-thymidine incorporation assays. The TCR variable regions of these hsp65-reactive T cells were characterized by polymerase chain reaction with TCR AV- and BV-specific primers and by DNA sequence analysis of the third complementarity-determining region (CDR3).

RESULTS

The hsp65-reactive T cells derived both from RA patients and controls preferentially recognized the 1-170 and 303-540 regions of hsp65 and did not cross-react with human hsp60. The hsp65-reactive T cell clones derived from RA patients displayed a restricted TCR AV and BV gene usage, which can be attributed to the limited clonal origin(s) of the independent T cell clones, as evidenced by CDR3 sequence analysis. These clonally expanded T cells were found in both PB and SF and in different inflamed joints of RA patients.

CONCLUSION

Our study suggests that there is in vivo clonal activation and expansion of mycobacterial hsp65-reactive T cells in patients with RA.

The role of molecular chaperones in mitochondrial protein import and folding

Molecular chaperones play a critical role in many cellular processes. This review concentrates on their role in targeting of proteins to the mitochondria and the subsequent folding of the imported protein. It also reviews the role of molecular chaperons in protein degradation, a process that not only regulates the turnover of proteins but also eliminates proteins that have folded incorrectly or have aggregated as a result of cell stress. Finally, the role of molecular chaperones, in particular to mitochondrial chaperonins, in disease is reviewed. In support of the endosymbiont theory on the origin of mitochondria, the chaperones of the mitochondrial compartment show a high degree of similarity to bacterial molecular chaperones. Thus, studies of protein folding in bacteria such as Escherichia coli have proved to be instructive in understanding the process in the eukaryotic cell. As in bacteria, the molecular chaperone genes of eukaryotes are activated by a variety of stresses. The regulation of stress genes involved in mitochondrial chaperone function is reviewed and major unsolved questions regarding the regulation, function, and involvement in disease of the molecular chaperones are identified.

Innovative treatment approaches for rheumatoid arthritis. T-cell regulation

There is considerable evidence to implicate T cells in the pathogenesis of rheumatoid arthritis (RA). They initiate and sustain inflammation and therefore are attractive targets for immunotherapy. Several strategies targeting T cells have been tried in RA. The use of monoclonal antibodies to deplete T cells have been used extensively but with little success. Studies have shown that T cell depleting antibodies produce profound peripheral blood lymphopenia but they are less effective in depleting lymphocytes in the joint. Since clinical efficacy is likely to depend on depleting almost all synovial lymphocytes, high doses of monoclonal antibodies would have to be given. However, the invariably severe peripheral blood lymphopenia induced by such a regimen is likely to result in profound immunosuppression. Therefore, this strategy has been abandoned and recent attempts have been made to induce tolerance in RA. In animal models of RA, treatment with high dose non-depleting anti-CD4 monoclonal antibody protects them from arthritis induced by injection of streptococcal cell wall. In addition, it leads to a state of anergy which protects the animals from arthritis induction without further treatment with anti-CD4 monoclonal antibody. This is currently being used in clinical trials of RA. Other tolerance inducing treatment strategies include T cell or T cell receptor vaccination and oral tolerance. The former is particularly difficult since the rheumatoid arthritogenic antigen and the pathogenic T cell remain unknown. The latter has shown promise in placebo controlled trials although the ideal dosage remains unknown. The mechanism of action of oral tolerance involves either immunosuppressive T cell cytokines, T cell anergy or depletion.

Klebsiella pneumoniae-reactive T cells in blood and synovial fluid of patients with ankylosing spondylitis. Comparison with HLA-B27+ healthy control subjects in a limiting dilution study and determination of the specificity of synovial fluid T cell clones

OBJECTIVE

To study the frequency of Klebsiella pneumoniae-responsive T cells in the peripheral blood (PB) of ankylosing spondylitis (AS) patients compared with that in healthy HLA-B27+ donors, and to examine T lymphocyte clones (TLC) derived from AS patient synovial fluid (SF) for the presence of Klebsiella reactivity.

METHODS

Limiting dilution analysis of PB T cells in 8 patients with active AS and in 8 HLA-B27+ healthy subjects was used to determine the frequency of PB T cells responsive to K pneumoniae and Escherichia coli GroEL. SF T cells from a patient with active AS were cloned, and 125 TLC were characterized in proliferation assays.

RESULTS

There were fewer T cells in the PB of AS patients that reacted with K pneumoniae than in the PB of healthy HLA-B27+ subjects. The frequencies of E coli GroEL-responsive T cells were approximately 5-10 times lower in all subjects tested (healthy donors and AS patients), but without significant differences between the 2 groups. Two CD4+ TLC that recognized K pneumoniae (1 cross-reactive with E coli) as well as 3 TLC that recognized GroEL (2 CD4+, 1 T cell receptor gamma/delta+) were isolated from the SF of a patient with actige AS.

CONCLUSION

Our results indicate that there is a quantitative reduction of K pneumoniae-responsive T cells in the PB of AS patients as compared with healthy controls. This may reflect a defective peripheral T cell defense in the immune response to Klebsiella and may allow bacterial antigens to reach the synovium, where they initiate specific T cell responses.

Expression and immune recognition of stress proteins in sarcoidosis and other chronic interstitial lung diseases

Stress proteins (SP) are major immunogens in a number of microbial infections and have been implicated in some autoimmune diseases. The aetiology of sarcoidosis, a non-caseating granulomatous disease, remains unknown, but mycobacteria as well as autoimmunity have been considered. In the present study, patients diagnosed with sarcoidosis and other interstitial lung diseases (ILD), as well as healthy volunteers were studied to determine: (i) the level of expression of SP in alveolar macrophages and blood monocytes; (ii) the serum levels of antibodies specific for mycobacterial SP65 and SP70; and (iii) the reactivity of peripheral blood and alveolar lymphocytes to mycobacterial SP65. Our results suggest that SP are expressed constitutively at high levels in alveolar macrophages, retrieved by bronchoalveolar lavage, from all individuals regardless of health status. In contrast, freshly isolated blood monocytes express low levels of SP, which are, however, readily upregulated following exposure to IFN-gamma and TNF-alpha. Lymphocyte reactivity and presence of antibodies against mycobacterial SP may reflect the current state of in vivo inflammation rather than the cause of inflammation.

The pathogenesis of rheumatoid arthritis and the development of therapeutic strategies for the clinical investigation of biologics

This review discusses current concepts of the pathogenesis of rheumatoid arthritis. It is proposed that RA is a T cell mediated disease following which a large number of subsequent inflammatory events are unleashed. Many of the pathogenetic steps are targets for new therapies including biologics. Laboratory, clinical and radiological methods of assessing disease activity are sufficiently sensitive and reproducible to permit their use in multicentre studies capable of detecting a biologic with disease modifying activity. The clinical assessment of the efficacy and toxicity of biologics poses unique problems. These have been illustrated by the example of 3 monoclonal antibodies directed against ICAM-1, CD4 and TNF alpha. The main role of most biologics may be to pinpoint important therapeutic targets which can be attacked by more easily administered and less costly xenobiotic drugs.

Joint-derived T cells in rheumatoid arthritis proliferate to antigens present in autologous synovial fluid

The histopathological features of rheumatoid joint-inflammation suggest that an antigen-driven activation of T cells plays a central role in the onset and/or perpetuation of the inflammatory process. However, the disease-associated antigens responsible for the activation of T cells in the joint are unknown. In this project we study the response of IL-2 expanded T-cell lines from the synovial fluid (SF) of rheumatoid arthritis (RA) patients against autologous SF in a proliferation assay. Sixteen out of 32 RA patients were found to have CD4+ T cells that proliferate in response to autologous SF. The presence of T cells able to respond to SF antigens in inflamed joints suggests that these T cells play an active role in the pathogenesis of RA. T cell clones reactive to autologous SF were isolated from SF-derived T-cell lines of two RA patients. All clones were of the CD4+, CD8-, alpha/beta+ phenotype. SF-reactivity of T-cell clones from the DR4/DR12-positive RA patient was restricted via the Dw4 subtype of DR4. SF reactivity of T cells of the DR12/DR15 patient was DP-restricted. Some of the T-cell clones responded specifically to autologous and not to allogeneic SF, whereas others revealed responsiveness against a limited number of allogeneic SF samples. The (restricted) specificity of T cells towards autologous SF antigens is indicative for heterogeneity of the epitopes recognized and argues against ubiquitous nonpolymorphic joint constituents as the relevant antigens recognized by the SF-autoreactive T cells.

Absence of Mycobacterium tuberculosis DNA in synovial fluid from patients with rheumatoid arthritis

OBJECTIVES

To determine whether Mycobacterium tuberculosis DNA can be detected in synovial fluid of patients with rheumatoid arthritis (RA).

METHODS

The polymerase chain reaction was applied to cellular components of synovial fluid.

RESULTS

No evidence of M tuberculosis DNA was found in synovial fluid from 31 patients with RA and 13 control patients.

CONCLUSION

The findings do not support a role for persistent M tuberculosis infection in the pathogenesis of RA.

Group A streptococcal antigens and superantigens in the pathogenesis of autoimmune arthritis

Evidence from repeated clinical observations and from a variety of experimental approaches implicates group A streptococci in the pathogenesis of the autoimmune arthritides. Several streptococcal antigens and superantigens have now been characterized and their properties suggest that they may be involved in the mechanisms which underlie these diseases, although other antigens and superantigens yet to be discovered may also be involved. The association between group A streptococcal infection and autoimmune arthritis offers a useful model for providing a long-elusive understanding of the role of bacterial infection in the pathogenesis of autoimmune disease.

Inflamed joints of patients with rheumatoid arthritis contain T cells that display in vitro proliferation to antigens present in autologous synovial fluid. Functional analysis on the basis of synovial-fluid-reactive T-cell clones and lines

The immunopathology of inflamed joints in patients with RA is thought to result from an antigen-driven T-cell response. The antigen(s) responsible for the activation of synovial T cells, however, are as yet unidentified. In this study, we tested SF as a potential source of (auto)antigen(s). Five of 15 IL-2-expanded T-cell lines generated from SF cells of RA patients displayed a proliferative response to autologous SF. Five CD4+CD8-alpha beta TCR+SF-reactive T-cell clones obtained from responder T-cell lines were studied in more detail. Three T-cell clones from one RA patient were found to recognize epitopes in autologous SF in the context of DR4(Dw4), and two T-cell clones of another RA patient responded to autologous SF in the context of the HLA-DPB1*0401 gene product. The two DP-restricted clones and one of the DR-restricted clones did not proliferate to 50 SF samples of other RA patients, whereas the remaining DR-restricted clones responded to one allogeneic sample. Sequence analysis demonstrated that the latter clones expressed identical V beta 6.9 + TCR beta chains. This was also found for the (V beta 19+) DP-restricted clones. Proliferation of SF-reactive T cells was not only obtained with SF of the joint that had contained the T cells, but also with autologous SF of other affected joints. Together, these findings indicate that epitopes able to stimulate synovial T cells differ among RA patients, but may be similar within multiple joints of an individual patient. The presence of T cells able to respond to SF antigens in inflamed joints suggests that these T cells play an active role in the pathogenesis of RA.

T-cell antigen receptors in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic disease of unknown etiology characterized by chronic inflammation mainly in the joints. Several lines of evidence suggest that T cells are involved in the pathogenesis of the disease. RA is associated with certain HLA-DR alleles. Studies analyzing T-cell receptor transcripts in RA have found biased or preferential usage of certain V alpha and/or V beta gene segments by T cells infiltrating the synovial membrane or extravasating into the synovial fluid compared to peripheral blood. In certain patients few T-cell antigen receptor (TCR) clones dominated the infiltrating T cells, suggesting that T cells from the synovial membrane or the synovial fluid comprise oligoclonal populations of T cells. However, other studies have found a polyclonal population of T cells. In interpreting these results the phase of the disease (early vs. late RA), the source of T cells and the limitations of the methods used in these studies should be taken into consideration. However, it appears that synovial T cells comprise oligoclonal populations of T cells and that there is a bias towards particular TCR gene segments, although a specific TCR gene segment in RA has not emerged.

The biased V gamma gene usage in the synovial fluid of patients with rheumatoid arthritis

Taking advantage of the reverse transcriptase-polymerase chain reaction (RT-PCR), we have analyzed T cell receptor gamma-chain mRNA of synovial fluid gamma/delta T cells from patients with rheumatoid arthritis (RA) in comparison with those of peripheral blood mononuclear cells (PBMC) from RA patients and healthy individuals. The quantitative RT-PCR method in conjunction with nucleotide sequencing revealed the frequent usage of the V gamma 3 gene segment in RA synovial fluid mononuclear cells (SFMC) (p < 0.01) which in PBMC of healthy individuals occurred rarely. PBMC of most healthy individuals expressed the V gamma 9 gene predominantly (p < 0.01) as expected. However, only half of RA patients showed elevated levels of the V gamma 9 gene expression in their PBMC. The gamma-chain mRNA containing the V gamma 3 gene in RA SFMC showed no conserved junctional sequence (complementarity-determining region 3). To investigate the nature of ligands recognized by the V gamma 3-bearing T cells, we analyzed V gamma gene usage of RA SFMC, RA PBMC, and normal PBMC stimulated with Mycobacterium tuberculosis (MT) or MT plus interleukin-2 since there is mounting evidence of high reactivity of RA SFMC to MT and mycobacterial heat-shock protein 65. However, the V gamma usage appeared to be mostly V gamma 9 in RA SFMC, RA PBMC and normal PBMC. Taken together these results suggest that an as yet unknown antigen(s) (other than MT) might select gamma/delta T cells expressing the V gamma 3 gene in RA SFMC.

Characterization of the circulating T-cell response after oral immunization of human volunteers with cholera toxin B subunit

The kinetics and phenotypic characterization of the in vitro cell proliferative response to the B subunit of cholera toxin were studied using peripheral blood mononuclear cells taken from human volunteers at frequent time points after primary and booster oral immunizations. The cells induced to proliferate by oral immunization secreted IL-3, and lipopolysaccharide depletion and depletion of B cells did not affect proliferation. Flow cytometry demonstrated that activated cells were CD3- and CD4-positive. These findings indicate primed T cells proliferating specifically to the B subunit. The kinetics of the response suggested trafficking in the peripheral circulation of primed T cells from the gut, with a peak stimulation index of between 7 and 93 after first immunization, and a precursor frequency of primed cells of between 1 in 25,400 and 1 in 72,390. There was close correlation between the serum antitoxin IgA antibody levels and observed proliferation.

Antibody response of restricted isotype to heat shock proteins in juvenile chronic arthritis

Synovial fluid and peripheral blood mononuclear cells from juvenile chronic arthritis (JCA) patients have previously been shown to exhibit substantial proliferative responses to both human and mycobacterial heat shock protein (hsp) 65. We investigated the nature of the antibody response to mycobacterial and E. coli hsp 65 and human and E. coli hsp 70 in 56 JCA patients using an ELISA. Elevated levels of antibodies to both human and E. coli hsp 70 were demonstrated. With hsp 65, raised levels of antibodies to the mycobacterial but not the E. coli protein were detected. Overall, 48% of patient serum samples contained antibodies of at least one isotype to mycobacterial hsp 65. These antibodies were predominantly of IgG and IgM isotype, a finding in contrast to adult rheumatoid arthritis, where IgA and IgG isotypes are most often detected.

Heat shock (stress) proteins and autoimmunity in rheumatic diseases

The rheumatic diseases (RDs) are characterized by acute and chronic inflammation, and autoimmunity plays a major role in their pathogenesis. RDs are for the most part of unknown etiology, but recent evidence indicates that heat shock or stress proteins (HSPs) may have an important role in the etiology/pathogenesis of RDs. HSPs are produced by prokaryotic and eukaryotic cells and are grouped according to molecular weight. Phylogenetically, HSPs are very old and are remarkably conserved molecules in evolution from bacteria to humans. HSPs are induced by a variety of cellular stresses in addition to heat; cognates are expressed constitutively and are essential in a number of normal functions. Some HSPs serve as molecular chaperones, the latter defined as proteins that mediate folding of other polypeptides and either promote their assembly into oligomeric structures or disassemble the final product. Conservation of structure and function of many HSPs may provide a link between immunity to infection and the autoimmune features of RDs. Evidence is reviewed from clinical and laboratory observations that diverse microbial agents, including viruses, bacteria, and parasites, may have putative roles in the development and pathogenesis of some RDs. HSPs also are discussed in relation to the major histocompatibility complex, HLA antigens, and disease associations and how they may alter the balance between tolerance and autoimmunity. Studies are reviewed that are supportive or nonsupportive of the concept of microbial infection associated with autoimmunity; individuals first react to microbial immunizations or infections with enhanced cellular/humoral responses to the agent's HSPs. With the enhanced immune response, cross-reactivity may occur with an HSP of the stressed host because of structural similarities to the microbial HSP. If all of these events occur, the host's homologous HSP or stressed cells now become true autoantigen(s). This sequence has implications for the etiology of immune-mediated RDs, the concept of epitope sharing, and the accompanying autoimmunity. A recurring theme emphasized in some reports to understand better the role of HSPs in autoimmunity is the need to select patients with early-onset disease. A minor subpopulation of T lymphocytes express a CD3-associated T-cell receptor (TCR) heterodimer composed of gamma and delta polypeptide chains. The gamma delta + T cells have several unique features. When analyzed by the polymerase chain reaction, lymphocytes with TCR-gamma delta appear to reflect the polyclonal expansion of preexisting gamma delta clones. They are found in peripheral lymphoid tissue in very low percentage (< 5%) but may represent the majority of T cells within epithelial tissue.(ABSTRACT TRUNCATED AT 400 WORDS)

Synovial fluid antigen-presenting cell function in rheumatoid arthritis

We have previously demonstrated enhanced synovial fluid (SF) antigen-presenting cell (APC) function in inflammatory arthritis patients selected on the basis of marked SF mononuclear cell (MNC) responsiveness to reactive arthritis-associated bacteria (Clin Exp Immunol 1990; 79:189-94). In this study we have assessed whether similarly enhanced synovial APC function is present in other inflammatory arthritis patients by using two assay systems to study 18 rheumatoid arthritis patients whose MNC responsiveness had not been determined in advance. We demonstrate that rheumatoid SF APC are much more potent than peripheral blood (PB) APC in stimulating the responses of autologous PB T cells to a range of recall antigens. In addition, SF APC are shown to be efficient stimulators of the antigen-specific responses of MHC-compatible, cloned T cells. Enhanced synovial APC function is thus likely to be a general feature of inflammatory arthritis and may play an important role in its pathogenesis.

Heat-shock proteins: immunity and autoimmunity

Antigens from a wide variety of pathogens have been identified as members of conserved heat-shock protein families, sharing upwards of 50% amino acid identity with corresponding host-cell proteins. Analysis of the responses to these conserved antigens may provide insights into regulation of the immune system during infection and autoimmunity.

High frequency of cord blood lymphocytes against mycobacterial 65-kDa heat-shock protein

A high frequency of nonadherent mononuclear cells in human cord blood proliferates in response to mycobacterial 65-kDa heat-shock protein. The frequency range in cord blood is not different from that in peripheral blood of Bacillus Calmette-Guérin vaccinated adults. In comparison we found 10 to 100 times lower frequencies to purified protein derivative in nonadherent cord blood mononuclear cells than in adult peripheral blood mononuclear cells. These findings may provide experimental support for Cohen's theory of the immunological homonculus.