Immunoregulatory abnormalities in familial Mediterranean fever

Concanavalin A (Con A)-activated suppressor cells from 4 patients with familial Mediterranean fever (FMF) and 16 normal volunteers were tested for suppression of proliferation of phytohemagglutinin (PHA)-stimulated responder cells from normal volunteers. The mean (±SE) percentage suppression by each FMF patient (4 ± 3, 2 ± 2, 8 ± 3, and 9 ± 4) was significantly ( P < 0.0005) less than the mean percentage suppression by 16 normal volunteers (44 ± 4). Cells from 2 of the FMF patients were also tested as responder cells. Con A-activated cells from normal volunteers did not suppress the proliferation of PHA-stimulated responder cells from one of these FMF patients (8%) but did suppress responder cells from the second FMF patient (43%). Furthermore, Con A-activated cells from two milk-allergic patients (suppressing 63% in coculture with responder cells from a normal volunteer) did not suppress responder cells from this second FMF patient (4%). Thus, FMF is associated with two immunoregulatory abnormalities: defective suppressor cell and abnormal responder cell function.