Lymphocytotoxic autoantibodies in progressive systemic sclerosis

Detection of CD4(+) T-cell antibodies in a patient with idiopathic CD4 T lymphocytopenia and cryptococcal meningitis

Idiopathic CD4(+) T lymphocytopenia (ICL) is defined as a CD4(+) T-cell count <0.3 x 10(9)/l or <20% of the total T-cell count on two occasions in the absence of any immunodeficiency disorder or therapy associated with reduced CD4(+) T-cell count. Although several mechanisms of ICL have been reported, the pathophysiology is still largely unknown. This case report describes a patient who presented with cryptococcal meningitis and was subsequently discovered to meet the criteria for ICL. Flow cytometric analysis of the patient's peripheral blood mononuclear cells revealed antibodies coating a much larger proportion of his CD4(+) T cells (33.61%) than the CD4(+) T cells of normal donors (3.94 +/- 1.77%). The reasons behind the development of these autoantibodies are explored.

Direct binding of anti-DNA topoisomerase I autoantibodies to the cell surface of fibroblasts in patients with systemic sclerosis

OBJECTIVE

Fibroblasts play a crucial role in the development of systemic sclerosis (SSc), and antifibroblast antibodies (AFAs) capable of inducing a proinflammatory phenotype in fibroblasts have been detected in the sera of SSc patients. This study examined the prevalence of AFAs in SSc and other diseases and the possible correlation between AFAs and known antinuclear antibody specificities in SSc patients.

METHODS

Sera from 99 patients with SSc, 123 patients with other autoimmune and nonautoimmune diseases, and 30 age- and sex-matched healthy controls were examined. AFA prevalence was assessed by flow cytometry and further characterized by indirect immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and immunoblotting. Anti-topoisomerase I (anti-topo I) from SSc sera were purified by affinity chromatography on topo I.

RESULTS

AFAs were more common in SSc patients (26.3%) than in any other disease groups studied. The presence of AFA was significantly associated with pulmonary involvement and death. AFA-positive sera from SSc patients bound to all human and rodent fibroblasts tested, but not to human primary endothelial cells or smooth muscle cells. All SSc AFAs strongly reacted with topo I by ELISA and immunoblotting. The binding intensity of SSc AFAs correlated strongly with reactivity against topo I on immunoblots of fibroblast extracts and with the immunofluorescence pattern typical of anti-topo I on permeabilized cells. Total IgG and affinity-purified anti-topo I from AFA-positive SSc sera were found to react with the surface of unpermeabilized fibroblasts by flow cytometry as well as by immunofluorescence and confocal microscopy.

CONCLUSION

This is the first report establishing that AFAs in SSc are strongly correlated with anti-topo I and, furthermore, that anti-topo I antibodies themselves display AFA activity by reacting with determinants at the fibroblast surface.

Autoantibodies to fibroblasts induce a proadhesive and proinflammatory fibroblast phenotype in patients with systemic sclerosis

OBJECTIVE

Fibroblasts play a major role in the development of systemic sclerosis (SSc), and the occurrence of serum autoantibodies reacting with fibroblast plasma membrane antigens in SSc has been reported. This study was undertaken to investigate whether IgG from SSc sera that react with human fibroblasts modulates the fibroblasts' function.

METHODS

Sera from 69 patients with SSc (28 with limited cutaneous SSc [lcSSc] and 41 with diffuse cutaneous SSc [dcSSc]), 30 patients with sarcoidosis, and 50 matched healthy controls were examined. We evaluated antibody binding to human skin and lung fibroblasts by cell-based enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence, and flow cytometry. We further investigated the ability of purified IgG to modulate 1) intercellular adhesion molecule 1 (ICAM-1) expression, 2) U937 cell adhesion to fibroblasts, and 3) fibroblast steady-state messenger RNA (mRNA) levels of interleukin-1alpha (IL-1alpha), IL-beta, and IL-6, and IL-6 protein production.

RESULTS

Of 69 SSc sera tested by cell-based ELISA, 58% bound to normal skin and lung fibroblasts. The prevalence of binding was significantly higher in dcSSc than in lcSSc (P < 0.05). Only IgG from SSc sera that were positive for antifibroblast antibody (AFA) induced a dose-dependent up-regulation of ICAM-1 expression and IL-6 production, enhancement of U937 cell adhesion, and increased levels of IL-1alpha, IL-1beta, and IL-6 mRNA in fibroblasts. Up-regulation of ICAM-1 mediated by AFA IgG was inhibited by the addition of IL-1 receptor antagonist, indicating an autocrine activation loop.

CONCLUSION

Our findings confirm the presence of AFAs in SSc sera and demonstrate, for the first time, that autoantibodies reacting with fibroblast surface molecules act as an extrinsic stimulus inducing fibroblast activation in vitro.

CD4+ and CD8+ T-lymphocytopenia in a filly with Pneumocystis carinii pneumonia

Decreased proportion of CD4+ and CD8+ T lymphocytes in peripheral blood likely contributed to susceptibility to Pneumocystis carinii in a foal. Cytological evaluation of bronchoalveolar lavage was required for identification of the pathogen and serial flow-cytometric analysis of peripheral blood lymphocytes documented transient low expression of CD4+ and CD8+ T lymphocytes. Although immunodeficiency is uncommon, it must be included in the differential diagnosis for patients suffering from chronic or opportunistic infections and may provide an indication for immunostimulant therapy.

Immunologic parameters in systemic sclerosis

BACKGROUND

Immunologic abnormalities seem to play an important role in important role in systemic sclerosis (SSc).

METHODS

We studied the following immune parameters to get more insight into SSc: autoantibodies (antinuclear antibodies (ANA), anti-Scl-70, anticentromere antibodies (ACA) subsets of lymphocyte subpopulations and markers of their activation, as well as serum levels of IL-2, the soluble IL-2 receptor (SIL-2R), IL-6 and its correlation to N-terminal procollagen-III propeptide (P III P), and finally, the IL-6 production by SSc and normal dermal fibroblasts.

RESULTS

In patients with active SSc, we found a reduced number of CD2+ T-lymphocytes and an increase in the expression of T-lymphocyte activation markers such as CD25+ and CD71+, HLA-DR Ia, as well as elevated serum levels of SIL-2LR and IL-6. SSc fibroblasts did not produce more IL-6 than normal fibroblasts in monolayer cultures.

CONCLUSIONS

Our data show that a wide range of immunologic parameters are altered in SSc. In general, T-helper (TH) lymphocytes are activated possibly because of reduced T-suppressor (TS) and natural killer (NK)-cell levels. TH may polyclonally stimulate B cells, which in turn produce higher amounts of autoantibodies. Our findings support the concept that TH cell-derived cytokines/growth factors stimulate matrix protein synthesis by fibroblasts, resulting in generalized fibrosis.

Idiopathic CD4+ T-lymphocytopenia--four patients with opportunistic infections and no evidence of HIV infection

BACKGROUND AND METHODS

We describe four patients without major risk factors for human immunodeficiency virus (HIV) infection, each of whom presented with severe opportunistic infections and was found to have idiopathic CD4+ T-lymphocytopenia. We performed assays to detect the presence of retroviruses and undertook immunophenotyping of subgroups of peripheral-blood lymphocytes.

RESULTS

The opportunistic infections at presentation included Pneumocystis carinii pneumonia, cryptococcal meningitis (two patients, one with concurrent pulmonary tuberculosis), and histoplasma-induced brain abscess. During 10 to 68 months of observation, none of the four patients had evidence of infection with HIV type 1 or 2 or human T-cell lymphotropic virus type I or II on the basis of epidemiologic, serologic, or polymerase-chain-reaction studies or culture, nor was there any detectable reverse transcriptase activity. Although all the patients had severe, persistent CD4+ T-lymphocytopenia (range, 12 to 293 cells per cubic millimeter), the CD4+ cell count progressively declined in only one and was accompanied by multiple opportunistic infections. All four patients had significantly reduced numbers of circulating CD8+ T cells, natural killer cells, or B cells (or all three).

CONCLUSIONS

These four patients had idiopathic CD4+ T-lymphocytopenia with opportunistic infections but no evidence of HIV infection. Instead of the progressive, selective depletion of CD4+ T cells characteristic of HIV infection, some patients with idiopathic immunodeficiency have stable CD4+ cell counts accompanied by reductions in the levels of several other lymphocyte subgroups.