Selective induction of rheumatoid factors by superantigens and human helper T cells.

Abstract

Production ofautoantibodies specific for the Fc region ofautologous IgG, called rheumatoid factors (RF), is a characteristic finding in patients with rheumatoid arthritis (RA). To study the requirements regulating the synthesis of these autoantibodies, we have cloned human helper T cells and co-cultured them with purified B cells.

Increased responsiveness of rheumatoid factor–producing B cells in seronegative and seropositive rheumatoid arthritis

“…Absence of RF production was confirmed in all normal individuals and in patients with seronegative disease by enzyme-linked immunosorbent assay (ELISA), as previously reported (2,13). The clinical characteristics of the 2 RA cohorts are summarized in Table 1.…”

“…Replicate cultures of serial dilutions of B cells were co-cultured with 1 X lo5 cloned T helper cells, and the frequency of Ig-producing cells was determined after 15-16 days. In the absence of additional T cell stimulation, no immunoglobulin production was observed (13).…”

“…Following SED stimulation, antibodies with RF activity are preferentially produced. The RF production is dependent on the cell-to-cell contact between the activated T cells and the B cells in the presence of SED (13). We have analyzed the molecular characteristics of SEDdriven B cells (16).…”

“…Peripheral blood mononuclear cells (PBMC) were isolated from heparinized blood samples by density gradient centrifugation on Ficoll-Hypaque. B lyrnphocytes were isolated from the blood of RA patients and control individuals, as previously described (13,15 Limiting-dilution analysis. To estimate frequencies of B cells secreting IgM, IgG, and RF, T cell-B cell cocultures were established according to previously described protocols (10).…”

“…Measurements of immunoglobulins and RF. Determination of IgM, IgG, and RF antibodies in culture supernatants has been previously described (10,13). Briefly, sheep antihuman polyvalent immunoglobulin (Sigma) was coated onto plates (Maxisorb; Nunc, Naperville, IL) in a carbonate buffer (pH 9.6) by overnight incubation at 4°C.…”