Deficient Lymphoid Cell-Mediated, PHA-Induced Cytotoxicity in Rheumatoid Arthritis Patients

Lymphoid cells from patients with rheumatoid arthritis were compared with those from healthy blood donors and from nonrheumatoid arthritis patients for the ability to manifest in vitro cytotoxicity against target cells in the presence of phytohemagglutinin (PHA) or anti-target cell antibodies. The PHA-induced cytotoxicity in the rheumatoid patient group was significantly lower than that of the blood donors (P < 0.01) and of the nonrheumatoid patients (P < 0.05). The rheumatoid arthritis patients appeared to fall into two groups, one with normal and one with distinctly subnormal PHA-induced cytotoxicity. No obvious differences were observed between these two groups with regard to duration or activity of the disease, treatment, autoantibodies, or the proportion in peripheral blood of T lymphocytes (E–RFC) or Fc-receptor-bearing lymphocytes (EA-RFC). There were no significant differences between the groups with regard to antibody-dependent cytotoxicity.