HLA-DP+ T cells and deficient interleukin-2 production in patients with systemic lupus erythematosus

Accelerated telomere shortening in rheumatic diseases: cause or consequence?

Accelerated aging of the immune system (immune aging), represented by telomere shortening, has been implicated in a variety of rheumatic diseases. Studies addressing telomere shortening in rheumatic diseases so far yielded controversial results. The current review aims to provide an overview on the role of immune aging in a plethora of immune-mediated conditions including systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus and osteoarthritis. The main question this review aims to answer is whether rheumatic diseases cause accelerated aging or that accelerated aging drives rheumatic diseases.

Striking alteration of some populations of T/B cells in systemic lupus erythematosus: relationship to expression of CD62L or some chemokine receptors

Recent studies have revealed new populations of T/B cells, including central/effector memory, follicular T cells and CXCR3+ or CXCR4+ B cells. In the present study, changes in these populations of CD4+ T cells were examined on the basis of the expression of CD62L, CCR7 and CXCR5 in patients with systemic lupus erythematosus (SLE) in relation to CCL21 and CXCL10. Changes in CXCR3+, CXCR4+ and CXCR5+ B cells were also examined. CD62L and various chemokine receptors were examined by flow cytometry analysis using monoclonal antibodies, and CCL21 and CXCL10 were examined by sandwich enzyme-linked immunosorbent assay. In patients with SLE, a decrease of naive T cells and an increase in the ratio of activated effector memory T cells were associated with an increase of CCL21 and CXCL10 in serum, although the correlation was not significant. An increase in the ratio of CXCR3+ B cells was also recognized. These results suggest that naive T cells are transferred to lymphoid tissue by CCL21, and that effector memory T cells are activated by CXCL10. It is also suggested that B cells responsive to follicular helper T cells tend to migrate to inflammatory tissue.

Decreased numbers of signal-joint T cell receptor excision circle-containing CD4+ and CD8+ cells in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) patients have a decreased number of peripheral blood T cells containing signal-joint T cell receptor excision circles (Sj TRECs), which are considered an indicator of thymic output. The objective of this study was to investigate the mechanism of the decrease in such T cells. Peripheral blood T cells from SLE patients were classified into CD4+ and CD8+ cells. Sj TREC levels were measured by real-time PCR. Telomerase activity was determined by the telomeric repeat amplification protocol assay. The numbers of Sj TREC containing CD4+ and CD8+ cells were lower in the peripheral blood of SLE patients than in the controls. A correlation was found between the numbers of Sj TREC-positive CD4+ and CD8+ cells. The level of TRECs is influenced by an increase in cell division. To examine this increase, telomerase activity as an indicator of cell division was measured simultaneously; however, there was no correlation between the Sj TREC level and telomerase activity. These results suggest that decreased thymic output occurs in SLE patients.

Genetic control of the spontaneous activation of CD4+ Th cells in systemic lupus erythematosus-prone (NZB x NZW) F1 mice

The F(1) hybrid of autoimmune hemolytic anemia-prone NZB and nonautoimmune NZW strains of mice has been studied as a murine model of systemic lupus erythematosus. Both NZB and F(1) hybrid mice show age-dependent spontaneous activation of peripheral CD4(+) T cells as reflected by the elevated frequencies of CD4(+) T cells positive for CD69 early activation marker. Both strains also show age-dependent abnormal decrease of the frequencies of CD62L(+) naive CD4(+) T cells and/or NTA260(+) memory CD4(+) T cells in the spleen. We studied the multigenic control of these abnormal features of peripheral CD4(+) T cells in (NZB x NZW) F(1) x NZW backcross mice by quantitative trait loci mapping and by association rule analysis. The abnormally elevated frequencies of CD69(+)CD4(+) T cells and decreased frequencies of CD62L(+) naive and/or NTA260(+) memory CD4(+) T cells were under the common genetic control, in which the interaction between MHC and a hitherto unknown locus, designated Sta-1 (spontaneous T-cell activation) on chromosome 12, plays a major role. The allelic effects of these loci likely predispose CD4(+) T cells to the loss of self-tolerance, and are responsible for the accelerated autoimmune phenotypes of (NZB x NZW) F(1) hybrid mice.

Telomerase activity and telomere length of peripheral blood mononuclear cells in SLE patients

We evaluated the clinical significance of the telomerase activity and telomere length of peripheral blood mononuclear cells (PBMC) in systemic lupus erythematosus (SLE). PBMC were isolated from 55 patients with SLE and the telomerase activity was measured by TRAP assay. The telomere length of PBMC was also measured in 30 of these subjects. As a control group, 45 healthy adults with no particular clinical history were studied. The results were compared with clinical data. In patients with active SLE, the telomerase activity of PBMC was significantly increased compared with the control group. In patients with inactive SLE, the PBMC telomerase activity was not different compared with the controls in their 20s, 30s and 40s, but it was significantly increased compared with the controls in their 50s. In SLE patients, the telomerase activity of PBMC was significantly correlated with modified SLEDAI. The telomere length of PBMC in younger SLE patients tended to be shorter than that in the controls, but no difference was observed in older patients. The correlation coefficient between the telomerase activity and telomere length of PBMC in SLE patients was not significant. Abnormalities in the telomerase activity and telomere length observed in SLE patients are considered to be important findings for evaluation of the pathology of SLE.

Immune abnormalities induced by human endogenous retroviral peptides: with reference to the pathogenesis of systemic lupus erythematosus

P15E is a specific sequence among the envelope gene (env)-encoded transmembrane proteins of exogenous and endogenous retroviruses. A synthetic peptide (CKS- 17) that shows homology to this p15E region in several species of retrovirus is known to induce immune abnormalities. In this study, we examined the effect of a synthetic peptide derived from a region of human endogenous retrovirus (HERV) clone 4-1 (lambda4 - 1) similar to sequences of CKS-17 on the induction of systemic lupus erythematosus (SLE)-related immune abnormalities. Our results indicated that this peptide could induce T-cell activation and anergy in normal peripheral blood mononuclear cells, and the peptide could also promote the production of interleukins IL-6 and IL-16. These phenomena are representative immune abnormalities observed in SLE patients. Thus, our findings support the possibility that HERV acts as a pathogen in human SLE.

CD154 expression and mRNA stability of activated CD4-positive T cells in patients with systemic lupus erythematosus

Abstract The expression of CD154 (CD40 ligand) on activated CD4+ T cells is known to be transient and tightly regulated for antigen-specific immune responses, and is increased and prolonged among patients with systemic lupus erythematosus (SLE). We investigated the regulation of CD154 expression by determining the protein and mRNA expression with PMA and ionomycin stimulation in CD4+ T cells, and confirmed their increase and prolongation in SLE T cells. Treatment with actinomycin D, a transcription inhibitor, after PMA and ionomycin stimulation was performed, and the findings revealed that the stability of CD154 mRNA increased significantly in activated SLE T cells compared with that of controls. However, alternations or abnormal sequences were not identified in the 3″ untranslated region, including AU-rich elements and CU-rich sequences, while their partial involvement in the posttranscriptional regulation of CD154 mRNA stability has been reported. With 96 h culture in vitro, the destabilization of CD154 mRNA was demonstrated, resulting in a corresponding decrease and normalization of surface expression on activated SLE T cells. We speculate that the CD154 expression on T cells from SLE patients may be increased and prolonged, with mRNA stabilization being related to a continuous stimulation in vivo.

Activated peripheral blood mononuclear cells detected in lupus patients using cDNA coding for proliferating cell nuclear antigen

Abstract The expression of proliferating cell nuclear antigen (PCNA) mRNA in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE) was measured by dot blot hybridization using a PCNA cDNA, and correlated with the percentage of PCNA-positive cells detected immunohistochemically using a monoclonal anti-PCNA antibody. PCNA-positive PBMCs were detected in 72.2% of SLE patients (n = 36), which is significantly more than among healthy controls. In addition, among those in whom PCNA expression was detected, the percentage of PBMCs expressing PCNA was significantly higher in SLE patients (mean 2.5% vs. 0.15%). The level of PCNA mRNA was increased in PBMCs from 83.3% of SLE patients, and was significantly correlated with the percentage of PCNA-positive cells (r = 0.54, P < 0.01) and with the disease activity score (r = 0.56, P < 0.01). A longitudinal study of two SLE patients confirmed that PCNA mRNA expression and the percentages of PCNA-positive cells varied in parallel with disease activity. Thus, an analysis of activated PBMCs from SLE patients using PCNA cDNA may be a useful method by which to estimate SLE disease activity.

Relationship between CD4(+)/CD8(+) T cell ratio and T cell activation in multiple myeloma: reference to IL-16

We found that the ratio of CD4(+) to CD8(+) T cells (CD4/CD8 ratio) was decreased in patients with multiple myeloma (MM) and that this decrease was significantly related to an increase of human leukocyte antigen (HLA)-DR expression by CD8(+) (but not CD4(+)) T cells (P<0.005). In addition, the serum level of interleukin (IL)-16 was significantly higher in stage III MM patients than in healthy controls (P<0.001). The decrease of CD4(+) T cells in MM may be mediated by activation of CD8(+) T cells derived cytokine IL-16. In addition, these T cell phenotypic changes and the IL-16 level appear to be useful indicators of disease activity.

Lessons from similarities between SLE and HIV infection

OBJECTIVE

We attempted to obtain deeper understanding of systemic lupus erythematosus (SLE) and human immunodeficiency virus (HIV) infection through comparative studies between both diseases.

METHOD

For this purpose, we reviewed and discussed lessons from similarities in both diseases based on our own and reported findings in literatures.

RESULT

Such comparative studies may contribute to the progress in understanding the clinical or pathogenetic features of these diseases.

CONCLUSION

Further studies into the relationship between SLE and HIV infection may bring to light important clues to assist in the development of better treatments for each disease.

A possible pathogenic role of CD8+ T cells and their derived cytokine, IL-16, in SLE

Current investigations into the role of CD8+ T cells and their derived cytokine, interleukin (IL)-16, in the induction of CD4+ T cell abnormalities in systemic lupus erythematosus (SLE) were reviewed and discussed on the basis of results mainly obtained in our laboratory.

Degradation of tryptophan in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE), a progressive autoimmune disorder, is associated with chronic stimulation of various components of the immune system. Since cell-mediated immunity is also activated, we were interested to test for abnormalities in tryptophan metabolism in SLE which may result from activation of indoleamine 2,3-dioxygenase by cytokines released during the immune response. We measured serum tryptophan and kynurenine concentrations in 52 patients with SLE as well as serum neopterin as an indicator for the degree of immune activation. Compared to controls, we found significantly decreased tryptophan and increased kynurenine concentrations in SLE. The extent of tryptophan catabolism correlates with neopterin concentrations or with the disease activity index. Tryptophan depletion may be associated with neurologic/psychiatric disturbances in patients suffering from SLE.

Relationship between CD4+/CD8+ T cell ratio and T cell activation in systemic lupus erythematosus

We investigated the relationship between the ratio of CD4+ to CD8+ T cells (CD4/CD8 ratio) and T cell activation, indicated by human leukocyte antigen (HLA)-DR expression, in patients with systemic lupus erythematosus (SLE). We found that the ratio was decreased in SLE patients and that this was significantly related to expression of HLA-DR by CD8+ (but not CD4+) T cells. These findings may assist in understanding the pathogenesis of SLE. In some SLE patients, the CD4/CD8 ratio and HLA-DR expression may be good indicators of therapeutic efficacy.

Inhibitory effect of interleukin-16 on interleukin-2 production by CD4+ T cells

Signalling through CD4 by human immunodeficiency virus (HIV)-1 envelope glycoprotein (gpl20) and/or anti-CD4 antibodies can promote T-cell activation and anergy. Interleukin (IL)-16 is a competence growth factor for CD4+ T cells that can induce a G0 to G1 cell cycle transition but cannot induce cell division. The receptor of this cytokine is thought to be the CD4 molecule, although the binding epitope of IL-16 differs from that of HIV. We have demonstrated that both HIV-1/gp120 and IL-16 induced CD4+ T-cell dysfunction, as indicated by suppression of mitogen-induced IL-2 production. Two anti-CD4 antibodies with different binding sites on CD4 also showed an inhibitory effect on IL-2 production. These results indicate that promotion of CD4+ T-cell anergy via the CD4 molecule does not depend on the binding sites of the CD4 ligands.

Expression of CD80 and CD86 on peripheral blood T lymphocytes in patients with systemic lupus erythematosus

CD80 and CD86 were detected in high amounts on circulating T cells in the peripheral blood of some patients with systemic lupus erythematosus (SLE), using flow cytometry and monoclonal antibodies. Patients with other connective tissue diseases did not have a high percentage of T cells expressing CD80 or CD86 in their peripheral blood. CD80 was expressed mainly on CD4 T cells, whereas CD86 was expressed on CD8 T cells, and these two populations were associated with particular clinical features. These two molecules were expressed on different T-cell populations and might have different roles in the generation and regulation of immune responses. Since high expression of CD86 on T cells was detected much earlier than the appearance of clinical features and a high titer of anti-DNA antibody, it may be a useful parameter for predicting the flare of SLE.

Exacerbation of systemic lupus erythematosus related to cytomegalovirus infection

We report two patients with systemic lupus erythematosus (SLE) in whom cytomegalovirus (CMV) infection may have played a significant role in the exacerbation or onset of symptoms. The first patient had thrombocytopenia and the second had proteinuria. CMV infection was observed in both patients when their symptoms developed.

Interleukin-2 and systemic lupus erythematosus--fifteen years later

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder in which multiple immunologic abnormalities have been described. In this review, we thoroughly analyse the impaired T cell production of, and response to, interleukin-2 (IL-2) characteristic of patients with SLE. Since it was first reported, several articles have provided us with enlightening, but somewhat confusing, data that reveal the complexity of the subject. The IL-2 production by T cells is part of a complex network in which a discrete alteration is capable of disrupting the whole system. On the other hand, regulatory mechanisms exist that, in an attempt to compensate the primary alteration, provoke secondary defects. Evidence indicates that this defect is not intrinsic, but rather, results from multiple microenvironmental influences that act on the T cell and modify its activation state and its cytokine production. Abnormalities in co-stimulatory mechanisms and in cytokines that may be related to the IL-2 production deficiency, have been described in patients with SLE. We also consider the information derived from murine SLE models, IL-2 knockout models and reports concerning the immune dysregulation present in patients with SLE.

Subsets of activated T cells in patients with systemic lupus erythematosus: the relation to cell cycle

The correlation among the various markers of activated T cells (soluble interleukin 2 receptor (sIL-2R), HLA-DR+ and HLA-DP+ T cells, proliferating cell nuclear antigen (PCNA) positive lymphocytes) were examined in patients with systemic lupus erythematosus (SLE), and related to the cell cycle. The concentration of sIL-2R and the proportion of HLA-DR+ T cells, HLA-DP+ T cells or PCNA+ lymphocytes were increased significantly as compared to that in normal subjects. And, the concentrations of sIL-2R correlated with the proportions of PCNA+ lymphocytes, but not with the proportions of HLA-DR+ T cells, HLA-DP+ T cells. The correlation between sIL-2R and PCNA+ lymphocytes was attributed to both indicators being increased during the G1B or S phase in normal T cells upon stimulation by phytohemagglutinin (PHA). Upon cell cycle analysis it was learned that activated T cells could be found in the G1A and the S phases.

Inhibitory effect of the immunosuppressant FK506 on apoptotic cell death induced by HIV-1 gp120

Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 may play a central role in inducing immunoregulatory disorders after HIV infection. The apoptotic death of normal human peripheral blood mononuclear cells was induced by priming with gp120 followed by stimulation with an anti-T cell receptor (TCR) antibody. Tumor necrosis factor-alpha produced by gp120-binding macrophages may be important to induce this cell death. Treatment of gp120-primed cells with an immunosuppressant (FK506) before TCR signaling inhibited apoptotic cell death, and this blocking effect of FK506 was concentration dependent. FK506 did not have any influence on cell growth and viability over the range of concentrations tested. These findings suggest that FK506 is a potentially useful drug in delaying the onset of AIDS after HIV infection.

Dual inhibitory and stimulatory activities in serum from SLE patients and lupus mice that regulate the proliferation of an IL-2-dependent T cell line

In serum and plasma from SLE patients, we have detected elevated levels of factors which regulate proliferative responses of CTLL cells to IL-2. Serum samples containing these factors have dose-dependent dual inhibitory and stimulatory activities on the proliferation of this IL-2-dependent T lymphocyte cell line. At high concentrations, the serum factors inhibit the proliferative responses of CTLL cells to IL-2. At low concentrations, they synergise with IL-2 stimulating the growth of cells. Similar inhibitory activity, but with lower titre, was also found to be elevated in sera of some MRL/lpr mice, an animal model of SLE. Functional characterisation of the serum factors shows that: (1) the inhibitory activity cannot be neutralised by exogenous IL-2; (2) the stimulatory activity is not due to the presence of serum IL-2 but synergy of the factor with IL-2; (3) the factors bind directly to CTLL cells but they do not bind to protein A; and (4) the serum factors are not dialysable but heat labile. The possible pathological implications of the serum factors, particularly for the defective T cell functions in lupus disease, are discussed.

Longitudinal study on the production of and cellular response to interleukin-2 in patients with systemic lupus erythematosus

Interleukin-2 (IL-2) has been proven to be a defective element in immune regulation in systemic lupus erythematosus (SLE). However, its course in time is unknown. We studied its production and cellular response in the peripheral blood cells of 30 SLE patients and 12 healthy subjects. In addition, we studied the spontaneous and lipopolysaccharide (LPS) induced production of IL-1, which have been found to be, respectively, increased and lowered in untreated SLE patients. Patients were studied at the outset, when still untreated, and at 1, 2, 6, 12, 18, and 24 months. At the outset, 18 had active disease and 12 were in remission. The decreased proliferative response of T cells to IL-2 and the deficient production of IL-1 upon LPS induction became normal after 6 months treatment, whereas the expression of high affinity IL-2 receptors took 18 months to become normal and the deficient production of IL-2 took 2 years. Despite clinical remission, the decreased capacity of T cells to absorb IL-2 persisted for 2 years. The effect of various prednisone dosages on the measured variables was evaluated. With intermediate doses of prednisone (20-45 mg), we observed the largest improvement in IL-2 production and in IL-1 production upon LPS stimulation. Higher doses of prednisone reduced also the spontaneous production of IL-1 and resulted in an increase in the expression of CD25+ cells. The addition of low doses of cytotoxic drugs (oral cyclophosphamide or azathioprine) resulted in an improvement in the capacity to absorb IL-2 and a reduction in spontaneous IL-1 production.(ABSTRACT TRUNCATED AT 250 WORDS)

B7/BB1 provides an important costimulatory signal for CD3-mediated T lymphocyte proliferation in patients with systemic lupus erythematosus (SLE)

Successful T cell activation via the T cell receptor (TCR)/CD3 complex requires at least one contact-dependent second signal delivered by costimulatory molecules, including the B7/BB1 molecule, that are present on antigen-presenting cells (APC). SLE is characterized by multiple complex lymphocyte abnormalities of undefined molecular origin. It is currently unclear whether an intrinsic defect of T cell or an underlying APC dysfunction is responsible for defective in vitro proliferation of T cells from patients with SLE. We planned the present experiments to ask whether the TCR/CD3-mediated and B7/BB1-costimulated T cell proliferation is normal in these patients. We used enriched T cell populations that were stimulated with an anti-CD3 MoAb in the presence of controlled quantities of functional B7/BB1 antigen. Freshly isolated T cells from 17 SLE patients (10 and seven patients with either active or inactive disease, respectively) and 11 normal individuals were cocultured with irradiated B7/BB1-transfected P815 cells or parental P815 cells in the presence of OKT3 MoAb at optimal and suboptimal concentrations for 2.5-7 days. Normal or SLE T cells responded similarly to stimulation via anti-CD3, in the absence of B7/BB1 antigen. A several-fold increase in T cell proliferation in the presence of B7/BB1 antigen was observed. Proliferation was inhibited in the presence of anti-B7/BB1 MoAb, but not with control MoAbs. Interestingly, dose-response curves and time kinetics of B7/BB1 costimulation were similar in T cells from patients with either active or inactive SLE at the time of study, and normal individuals. In addition, no differences in the IL-2 receptor release by T cells cultured under these conditions were observed between SLE patients and normal individuals. These results demonstrate that CD28 signalling is not intrinsically impaired in patients with SLE; further studies to investigate whether abnormal B7/BB1 expression is involved in the autoimmune process are needed.

A significant percentage of normal T lymphocytes express HLA-DP in the peripheral blood

HLA-DP expression has been widely investigated on T lymphocytes activated under different conditions. In the present study, a double staining procedure was used in flow cytometric experiments to define DP expression on normal peripheral blood T lymphocytes. In about two-thirds of the case analyzed, DP was expressed on a higher percentage of normal peripheral T lymphocytes than DR was. This was particularly true for 1 of the 16 cases investigated in which the percentage of T lymphocytes expressing DP was 46% and in which DP expression was mainly the prerogative of CD8+ and CD56+ lymphocytes.

Urine neopterin as a parameter of disease activity in patients with systemic lupus erythematosus: comparisons with serum sIL-2R and antibodies to dsDNA, erythrocyte sedimentation rate, and plasma C3, C4, and C3 degradation products

OBJECTIVES--To investigate urine neopterin as a parameter of disease activity in an unselected group of patients with systemic lupus erythematosus (SLE) and to study the relation between urine neopterin and certain patterns of organ disease and differing drug regimens in the treatment of SLE. METHODS--Neopterin was determined by high performance liquid chromatography in 115 early morning urine samples from 68 patients with SLE. Serum soluble interleukin 2 receptor (sIL-2R) and antibodies to double stranded DNA (dsDNA) were determined by enzyme linked immunosorbent assay (ELISA), and the erythrocyte sedimentation rate (ESR), plasma C3, C4, and C3 degradation products (C3dg) were measured in corresponding blood samples. Disease activity was scored using the British Isles Lupus Assessment Group (BILAG) index. RESULTS--Urine neopterin was significantly increased in patients with active and inactive SLE compared with the control group and was significantly higher in patients with active than in those with inactive SLE. Urine neopterin did not distinguish between subsets of patients with SLE with particular patterns of organ disease, as defined by the BILAG index, nor was its level primarily influenced by differing drug regimens. Levels of serum sIL-2R, antibodies to dsDNA, the ESR, and plasma C3, C4, and C3dg were also significantly different between the patients with active and inactive SLE. Unlike urine neopterin there was considerable overlap in the values of these parameters between the two activity groups. Highly significant correlations found between urine neopterin and serum sIL-2R, ESR, and plasma C3, C4, and C3dg suggest the close association of neopterin with clinical activity in SLE. Multivariate logistic regression analysis showed that urine neopterin > 300 mumol/mol creatinine was a highly significant predictor of disease activity with an odds ratio of 3.51. CONCLUSIONS--Determination of urine neopterin, a non-invasive, relatively simple and inexpensive measurement, appears to be the best parameter for assessing and monitoring disease activity and treatment in patients with SLE.

Susceptibility for infection-related glomerulopathy depends on non-MHC genes

BALB/c mice infected with Trypanosoma brucei and treated seven days after inoculation with Diminazene aceturate develop polyclonal B-cell stimulation, including production of antibodies to known nephritogenic autoantigens and glomerular disease associated with severe albuminuria. To investigate if the susceptibility for glomerular disease in this model is linked to MHC or non-MHC genes, we studied this disease in six mouse strains that were partly congenic for their MHC and partly congenic for their non-MHC genes. The course of the infection was measured by parasitemia and related to (auto)antibody production, proteinuria and glomerular deposition of immunoglobulins. The mouse strains could be divided into two groups. The first group consisted of the C57BL/6 (H-2b), C57BL/10 (H-2b) and B10.D2 (H-2d) strains, which proved to be relatively resistant to infection with Trypanosoma brucei (that is, spontaneous survival > 25 days). In sera of these mice antibodies to a broad range of antigens could be found 14 days after inoculation; no proteinuria was observed. The second group consisted of the BALB/c (H-2d), BALB.B (H-2b) and DBA/2 (H-2d) strains, which were relatively susceptible to the infection. In these animals proteinuria occurred and a broad polyclonal B-cell stimulation was seen 42 days after inoculation. No correlation was found between the specificity of circulating antibodies and the occurrence of proteinuria or a glomerular fluorescence pattern. These results indicate that in this model non-MHC genes govern the outcome of the infection as well as the development of polyclonal B-cell stimulation and proteinuria.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of mycobacterial infection in the lupus-prone MRL/lpr mice: enhancement of life span of autoimmune mice, amelioration of kidney disease and transient decrease in host resistance

We have used the MRL/lpr murine model of spontaneous lupus to investigate three questions in infection immunity: (1) does mycobacterial infection have any effect on the mortality of the autoimmunity-prone lpr mice?; (2) does the infection modify the progression of kidney disease of lpr lupus?; and (3) does the lpr gene change the resistance of mice to mycobacteria? Experimental infections were induced by intraperitoneal inoculation of 10(7) viable bacilli of Mycobacterium avium in 3 months old MRL/lpr mice and also in congeneic MRL/+ mice (lacking the lpr gene). MRL mice were sacrificed 1, 2.5 and 4 months after the M. avium injection. We found that infection caused lowering of urine protein concentration in lpr mice as compared with age-matched lpr controls. Mycobacteriosis also induced a marked decrease in the mortality of lpr animals, e.g. 85% of infected lpr mice reached the age of 7 months whereas only 10% of control lpr mice reached the same age. MRL/lpr mice showed, after 1 and 2.5 months of infection, higher mycobacterial loads than the congeneic non-lpr MRL mice; after 4 months of infection, however, differences in M. avium loads between the two groups of MRL mice became not statistically significant. We conclude that: (1) mycobacterial infection increases the life span of lpr mice; (2) the infection slows down the progression of kidney disease in the lupus-prone lpr animals; (3) the autoimmunity gene lpr is associated with a transient decrease in host resistance to mycobacteria.

T- and B-cell abnormalities in systemic lupus

A wealth of T- and B-cell abnormalities has been described in systemic lupus erythematosus (SLE). In general, T and B cells manifest evidence of intense in vivo activation, yet perform poorly when tested for in vitro responsiveness to exogenous antigen. The immune system behaves as if its commitment to self-responsiveness overrides the normal capacity to respond to immunogenic challenges. Many immunoregulatory abnormalities have been characterized, but their relation to disease remains controversial. Although a widely accepted unifying hypothesis for the vigorous autoantibody production and associated immune deficiency of SLE is lacking, it seems certain that the profound abnormalities of T and B cells in SLE are intertwined with the fundamental cause of this illness.

An early activation antigen of murine T cells recognized by monoclonal natural autoantibody NTA204 and the expression on T cells from aged NZB x NZW F1 mice with overt autoimmune disease

A monoclonal natural thymocytotoxic autoantibody NTA204 established from an autoimmune-prone NZB mouse reacted with the majority of thymocytes, all peripheral B cells, granulocytes and bone marrow myeloid cells, but not with peripheral resting T cells of normal mice. In aged NZB/W F1 mice with overt autoimmune disease, the population of NTA204+ CD4+ CD25- T cells was remarkably increased. The NTA204 antigen could be induced on splenic T cells from normal healthy mice as early as 3 hr after the initiation of culture with stimulant Con A, and was expressed on the vast majority in the 48-hr culture. The expression preceded that of other T cell activation antigens tested, CD25 and CD45R. Cell cycle analysis suggested that NTA204 is expressed at an early phase of G1A. T cells, particularly CD8+ T cells, in the allogeneic mixed lymphocyte culture (MLC) could be divided into two populations, NTA204+ and NTA204-. By immunohistochemical analysis, 30% of NTA204+ CD8+, but few NT204- CD8+ T cells were intensely positive for large cytoplasmic granules of perforin, an important cytolytic mediator of cytotoxic T cells. Thus the increased population of NTA204+ T cells in aged NZB/W F1 mice appear to be activated T cells and might be at least partly involved in the pathogenesis of disease in these mice. Immunoblotting analysis of Con A-activated splenic T cells showed that NTA204 molecules have a molecular mass of 49 Kd.

Activation markers on peripheral blood T cells from patients with active or inactive systemic lupus erythematosus. Correlation with proliferative responses and production of IL-2

Using various monoclonal antibodies to T cell activation molecules it has been shown that purified T cells from patients with active systemic lupus erythematosus overexpress the 4F2, IL-2R (CD25), HLA-DR and T10 antigens. T cells from patients with inactive disease had increased expression of VLA-1 and HLA-DR. Increased T10 expression on T cells from patients with active disease correlated inversely with the production of IL-2, whereas expression of CD25 was slightly increased after 3-day culture with either PHA or anti-CD3. These results provide further evidence of the in vivo activation of T cells in SLE and suggest that such activation comes slowly to a halt upon disease remission.