Autoantibody profiles in the sera of patients with Q fever: characterization of antigens by immunofluorescence, immunoblot and sequence analysis.

Recent reports have shown that some of the immunological aspects of Q fever, a rickettsiosis caused by Coxiella burnetii, could be related to self-antigen responses. The aim of this study was to determine the specificity of the autoantibody response of patients with acute and chronic Coxiella infections. Smooth muscle and cardiac muscle-specific autoantibodies were observed in significant percentages in acutely or chronically affected Q fever patients when compared to healthy volunteers. Moreover, the incidence of cardiac muscle-specific autoantibody was significantly higher among chronically ill patients compared to acutely ill patients. Moreover, a band of 50 kD of a HeLa extract was detected in most of the sera of individuals with chronic infections and previous sequence analysis suggests that this antigen presents a high degree of homology with the human actin elongation factor 1 alpha. Further research would be necessary to confirm if antibodies to human cytoskeletal proteins could be of clinical importance in chronically infected Q fever patients.

Evaluation of recombinant Ro/SSA, La/SSB, Sm, and U1 RNP autoantigens in clinical diagnosis.

This study comprises an analysis of the diagnostic usefulness of Ro/SSA, La/SSB, Sm and U1 RNP autoantigens obtained by DNA recombinant technology. We studied the presence of these autoantibodies in 33 patients with systemic lupus erythematosus (SLE) and 30 normal individuals by enzyme-linked immunosorbent assay (ELISA) using recombinant autoantigens and by Western immunoblot with these same antigens obtained from natural sources (rabbit thymus and human spleen). The strength of agreement between results found with these two techniques was moderate in the case of anti-Ro/SSA (kappa = 0.474, P < 0.001) and anti-U1 RNP (kappa = 0.566. P < 0.001) antibodies and almost perfect in the case of anti-La/SSB (kappa = 0871, P < 0.001) and anti-Sm (kappa = 0.833, P < 0.001). Furthermore, analysis of the disagreement between the two techniques evidenced a measurement bias for anti-Ro/SSA and anti-U1 RNP antibodies (Mc NEMAR'S statistic 13 and 11, respectively) whose direction, though difficult to define in the absence of a gold standard for such determinations, could be accounted for by the ELISA technique's greater tendency to produce positive results. Our conclusion is that the diagnostic usefulness of recombinant La/SSB and Sm autoantigens has been satisfactorily proven, whereas the case of the Ro/SSA and U1 RNP systems should be subject to further in-depth study of the autoepitopes recognised and the possible modifications which the latter might undergo as a result of their obtension from procariotic sources.

Hepatitis C virus antibodies and liver disease in patients with porphyria cutanea tarda.

The recent identification of the hepatitis C virus and development of assays to detect antibodies to hepatitis C virus has allowed assessment of the prevalence of hepatitis C virus infection in patients with a variety of liver and other diseases. The aim of this study was to investigate the prevalence of hepatitis C virus antibodies and severity of liver injury in patients with porphyria cutanea tarda. Sixty-two patients were studied. Serum samples were analyzed for liver function parameters and markers of hepatitis B virus infection. Frozen serum samples from 34 patients with porphyria cutanea tarda, obtained when patients were seen at the hospital for the first time, were analyzed for hepatitis C virus antibodies with enzyme-linked immunosorbent assays (first- and second-generation) and a recombinant immunoblot assay. As controls, serum samples from 19,788 blood donors, 40 patients with alcoholic liver disease and 138 hospitalized patients without liver disease were also tested for hepatitis C virus antibodies. Liver biopsy was performed in 42 porphyria cutanea tarda patients. Specimens were evaluated for steatosis, siderosis, fibrosis, severity of inflammation and the presence of cirrhosis. In addition, the degree of necroinflammatory change and fibrosis were quantitated with the histologic activity index described by Knodell et al. The prevalence of hepatitis C virus antibodies in patients with porphyria cutanea tarda (62%) was higher than that in blood donors (0.79%), patients with alcoholic liver disease (17.5%) or hospitalized patients without liver disease (5.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between antinuclear antibodies and the autoimmune rheumatic diseases and disease type and activity in systemic lupus erythematosus using a variety of cultured cell lines.

Antinuclear activity was assessed in serum samples from a series of 40 patients with differing clinical subsets (including renal and neurological disease) of systemic lupus erythematosus (SLE) against a transformed keratinocyte line (SvK14)* and normal human keratinocytes. Paired serum samples were studied during disease activity and inactivity, and the effects of ultraviolet radiation on the availability of nuclear antigens in the cell substrates were assessed. Serum samples from 20 healthy controls and 40 disease controls, comprising 10 patients each with rheumatoid arthritis, Sjögren's syndrome, scleroderma, and myositis, were also studied. The keratinocytes all provided sensitive substrates for the detection of antinuclear antibodies (ANAs), and in normal keratinocytes treated with ultraviolet radiation nuclear antigens were exposed on the cell surface. There was no correlation between ANAs and disease activity or patterns so, apart from assisting diagnosis, the detection of ANAs is of little relevance to predicting disease activity.

Abnormal B cell function in haemophiliacs and their relationship with factor concentrates administration.

The present study was performed to evaluate B cell function in haemophiliacs. Spontaneous and pokeweed mitogen (PWM)-induced immunoglobulin (Ig) production was determined by ELISA in the supernatants of cultured peripheral blood lymphocytes (PBL) from 14 haemophiliacs and 17 normal donors. Spontaneous IgM, IgA and IgG production was three times higher in patients than normal controls, while PWM-induced IgM, IgA and IgG production was markedly reduced in patients compared to normal donors (P less than 0.025). Allogeneic co-cultures of haemophiliacs and normal B plus T cell fractions revealed that these results are due to a defect of the patients' T cell depleted fraction. These abnormalities were not found in three patients who had received no clotting factor concentrates for at least 1 year prior to the study. Additionally, the annual amount of clotting factor concentrates received by treated patients correlates well with the enhancement of spontaneous Ig production (r = +0.688, P less than 0.02), the decrease of PWM-induced Ig secretion (r = -0.655, P less than 0.02), and the elevation of serum IgG levels (r = +0.610, P less than 0.05). These findings suggest that the administration of clotting factor concentrates play an important role in the altered B cell function in haemophiliacs.

Disorders of regulatory T cells in patients with selective IgA deficiency and its relationship to associated autoimmune phenomena.

In vitro lymphocyte function of 13 patients with selective IgA deficiency was studied. IgG, IgA and IgM secretion by pokeweed mitogen-stimulated peripheral blood lymphocytes from normal donors and IgA deficient patients was measured by an enzyme-linked immunosorbent assay. Addition of concanavalin A or hydrocortisone and co-cultures of B and T cell enriched populations from patients and normal donors, allowed us to investigate B cell Ig production and T cell regulatory abnormalities. IgA production by these patients' B cells was either absent or very low, as compared to their total Ig production, even in the presence of optimal T cell help. Several T cell immunoregulatory abnormalities were seen in different patients. A moderate increase in suppressor activity selective for IgA production was observed in some, but does not appear to play a major role in the pathogenesis of the IgA deficiency. In others, with associated autoimmune phenomena, a decrease in suppressor T cell function was found.