Depressed primary in vitro antibody response in rheumatoid arthritis.

We have studied the primary in vitro antibody response toward a hapten in cultures of peripheral blood lymphocytes from twenty-two patients suffering from regular rheumatoid arthritis (RA). These patients were not receiving immunosuppressive drugs or corticosteroids and had not taken Aspirin or non-steroidal anti-inflammatory agents for at least 72 hr. The control groups included thirty-two healthy subjects and twenty-seven control patients. The mean anti-TNP response of the RA patients was significantly lower than that of both control groups. No pre-existing anti-TNP or IgG response could be detected. A search for suppressor cells in co-cultures of RA and normal lymphocytes was negative. On the contrary, the extent of allogeneic enhancement in such co-cultures was comparable to that observed when control lymphocytes were co-cultured. RA serum added to normal lymphocytes cultures showed a dramatic inhibitory effect in only two out of nine cases. A follow-up study has strongly suggested that RA lymphocytes could increase their in vitro antibody response upon treatment.