In vivo and in vitro responses to autologous IgG in patients with rheumatoid arthritis

The presence of rheumatoid factor in patients with rheumatoid arthritis remains unexplained and may be etiologically important. An attempt has been made to determine whether patients with seropositive rheumatoid arthritis show basic immunologic responses to IgG. Various immunologic parameters of antigen recognition were measured in 9 patients and 3 controls. No immediate or delayed cutaneous hypersensitivity was noted to native or aggregated autologous IgG, nor could in vitro lymphocyte blast cell transformation be induced with these proteins. Rebuck skin windows showed no unusual responsiveness to native IgG. The negative results indicate that either IgG is not the immunogen responsible for rheumatoid factor or that patients with rheumatoid arthritis retain a state of partial tolerance. Evidence supporting the concept that rheumatoid factor may interfere with the phlogistic potential of aggregated γ‐globulin was also found.