Cutaneous immunofluorescence in ankylosing spondylitis. Absence of correlation with disease activity.

Biopsy specimens of normal skin from 43 patients with ankylosing spondylitis (AS) were studied for immunoglobulin and complement deposition by immunofluorescence and for histological abnormalities by light microscopy. The results were compared with those of 17 healthy subjects. Perivascular deposits of IgA, IgG, IgM and C3 were found in 26, 47, 56 and 33%, respectively, of the patients with AS. Skin deposits of IgA, IgG and C3 occurred significantly more frequently in patients with AS compared to healthy subjects. Perivascular mononuclear cell infiltration was found in only 8 (19%) of the patients with AS. The results of both immunofluorescence and histologic studies did not correlate with disease duration, disease activity, extraarticular features or the presence of circulating immune complexes. Our findings suggest a role of humoral immunopathological mechanisms in AS but also show that cutaneous immunofluorescence cannot serve as a marker of disease activity.

Spontaneous immunoglobulin synthesis by peripheral mononuclear cells in active rheumatoid arthritis.

Spontaneous production of immunoglobulins (Igs) by peripheral blood mononuclear cells (PBMC) in vitro was investigated to assess B cell activity in a group of 24 patients with rheumatoid arthritis (RA) with or without active joint disease and with or without rheumatoid vasculitis (RV) at the time of study. PBMC of patients with active arthritis (Ritchie index above 16) produced significantly more IgG and IgA than those of patients with inactive joint disease or those of 12 healthy controls. Enhanced production of IgG was found mainly among RA patients with concomitant RV, whereas markedly enhanced IgA production could also be found in patients without symptoms of RV. IgM production was only enhanced in two patients who had both active arthritis and RV. High production of IgG and IgA was probably due to increased numbers of Ig-secreting cells among freshly isolated PBMC, since the concentrations of Ig produced in vitro rose steadily, starting on day 0 and persisting throughout the entire culture period. Moreover, IgG and IgA concentrations measured after 7 days of culture showed significant correlations with the numbers of IgG- and IgA-containing plasma cells in PBMC on day 0. Comparison of the spontaneous production of Igs by PBMC with the levels of circulating immune complexes (CIC), showed that CIC levels were also significantly higher in active arthritis and in RV, but that there was no correlation between the CIC levels in individual patients and Ig production by their PBMC in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of immunofluorescent immunoglobulin inclusions in polymorphonuclear leucocytes for the detection of circulating immune complexes.

Cytoplasmic inclusions of immunoglobulins and complement, detected by fluorescent antibodies in polymorphonuclear leucocytes (PMNs) that have been incubated with sera of certain patients, are considered to represent immune complexes (IC). The usefulness of this test--the indirect PMN phagocytosis test (IPPT)--for the detection of circulating IC was investigated using preparations of free and heat-aggregated immunoglobulins. Free IgG and IgM were phagocytozed by PMNs at high concentrations only, while free IgA was not phagocytozed at all. Normal human serum slightly enhanced the uptake of free IgG and IgM, but not of free IgA. Aggregates of IgG and IgA underwent phagocytosis at low concentrations, but IgM aggregates were not taken up more readily than free IgM. The uptake of IgG aggregates decreased in the presence of serum, while there was no influence upon the phagocytosis of IgA aggregates. Phagocytosis of C3 occurred only with IgG aggregates. In the presence of aggregates of IgG or IgA the phagocytosis of free immunoglobulins of other classes, in particular IgM, increased. The results of the IPPT for patients' sera showed that inclusions of C3 were found more frequently in combination with IgA or IgM than with IgG. Comparison with the 125I-Clq binding assay and the anti-IgA inhibition binding assay disclosed significant correlation between the phagocytosis of IgG and the precipitation of 125I-Clq and between the phagocytosis of IgA and the results of the anti-IgA inhibition binding assay. The PMN phagocytosis test may be useful for the detection of IgG and IgA containing IC but inclusion of IgM and C3 should be interpreted with some reserve.