Abnormal in vitro immunoglobulin synthesis of lymphocytes and increased circulating immune complex in patients with ankylosing spondylitis.

To explore the immunopathogenetic mechanisms of hypergammaglobulinemia in ankylosing spondylitis (AS), the functions of B cell, helper T (OKT4) cell and suppressor T (OKT8) cell were examined, by using the co-cultivation technique for in vitro immunoglobulin biosynthesis, in 7 patients with active AS, 7 with inactive AS and 14 normal controls. Circulating immune complexes (CIC) in those subjects were also measured by a solid phase C1q binding assay. After B, OKT4 and OKT8 cells were separated from the heparinized peripheral blood, coculture of these cells which were either from the same patient, the same normal control, or their combination was carried out. The in vitro synthesized immunoglobulins were measured by a rate nephelometer (Immuno-chemistry system, analyzer II). The results were: In patients with active AS, the amounts of IgG and IgA synthesized by co-cultured B and T4 cells from patients (p) and T8 from the normal (n) were significantly higher than those of the normal controls; In patients with inactive AS, the amounts of IgG and IgA produced by co-cultured Bp + T4p + T8n, Bp + T4n + T8n, Bn + T4n + T8p, and Bn + T4p + T8p were significantly higher than those for the respective normal controls; The CIC in active AS was elevated significantly over that in the normal controls. These results suggest that in patients of AS, B cells and helper T cells are hyperactive, while suppressor T cells are depressed. The abnormal function of lymphocytes may cause elevated concentrations of immunoglobulins and CIC in the serum.