Defective IL2 production in active rheumatoid arthritis. Regulation by radiosensitive suppressor cells

The production of interleukin 1 (IL1) and interleukin 2 (IL2) by mononuclear cells (MNC) from untreated rheumatoid arthritis (RA) patients or healthy subjects were examined. After PHA stimulation, patient MNC or T cells produced varying amounts of IL2 that were related to the disease activity: patients suffering from active disease showed a scant production of IL2 while those who had a quiescent disease were high producers. The prior irradiation of unfractionated MNC induced a marked increase of the PHA-stimulated IL2 production in both active and quiescent patients compared to the moderate augmentation observed for controls. On the other hand, irradiation of enriched T cells had an enhancing effect only in the active RA patient group. Concurrently, we found that non T cells from active or quiescent RA patients were fully competent to produce IL1 upon LPS activation. Taken together, these findings suggest that the suppressive activity evidenced by irradiation could be mediated by non T cells in quiescent disease or in absence of illness. On the other hand, both radiosensitive suppressor T and non T cells may interfere in IL2 production by active RA patient lymphocytes.