Suppressor cell function in a family with familial Mediterranean fever.

Defective suppressor cell function has been demonstrated in several diseases but has not been tested in familial Mediterranean fever (FMF). We tested the ability of concanavalin A-activated suppressor cells from one family with FMF to inhibit the proliferation of phytohaemagglutinin-stimulated responder cells from normal volunteers. Four FMF patients tested between acute attacks had a mean (+/- s.e.) per cent suppression (5 +/- 2) which was significantly (P less than 0.0005) less than an FMF patient tested during a spontaneous remission (47 +/- 3), 10 healthy family members (41 +/- 6) and eight normal volunteers (45 +/- 4). Since FMF is inherited as an autosomal recessive disorder, deficient suppressor cell function is expressed in homozygotes between acute attacks, but not in a homozygote in spontaneous remission, homozygotes who are phenotypically normal, nor heterozygotes. This suggests that the suppressor cell abnormality in this family is probably related to the pathogenesis of FMF rather than representing a genetic marker of FMF or non-specific depression by disease activity.