Nonspecific suppressor cells in rheumatoid arthritis. Con A and PHA induced suppressor cell activity.

Suppression of the blastogenic response by autologous cells precultured with Concanavalin A (Con A) or Phytohemagglutinin (PHA) was studied in an in vitro system. The mean mitogen response of cells from normal individuals and from patients with Rheumatoid Arthritis (RA) in isologous plasma was similar. In isologous plasma there was no significant difference between the activity of Con A suppressor cells of normals and those of RA. Incubation of the cells in RA plasma abrogated the suppression in both normals and RA patients. In isologous plasma PHA suppressor cells were also induced in both groups, the levels being lower in the normals than in the RA group. PHA suppressor cell activity against PWM induced blastogenesis could not be engendered in normals. RA plasma abrogated PHA suppressor cell activity, especially in the RA group. The abrogating activity of RA plasma was heat stable, nondialysable and could be correlated with the presence of anti-lymphocyte antibodies in the RA plasma.