Cell-mediated immunity in rheumatoid arthritis. Discrimination between specific and non-specific effects of native and aggregated IgGs on leucocyte migration.

Leucocyte migration inhibition (LMI) by paired samples of autologous serum and synovial fluid IgG as well as homologous IgG and also heat-aggregated forms of all three IgGs was studied for patients with rheumatoid arthritis (RA) and compared with the response to these antigens by leucocytes from healthy individuals. Autologous and homologous serum IgGs did not markedly affect leucocyte migration, whereas synovial fluid IgGs caused occasional pronounced LMI with autologous (rheumatoid) leucocytes. Although aggregated IgG produced LMI in both RA patients and controls, the means of the migration indexes were significantly different between both groups. Peripheral blood mononuclear cells from RA patients and healthy controls were also cultured with both native rheumatoid and normal IgG; only supernatants from RA cells incubated with rheumatoid IgG showed LMI activity, in contrast to the other culture supernatants. These results indicate that LMI to native IgG in RA may represent a form of specific cell-mediated immunity, although LMI to aggregated IgG might be explained by non-specific factors.