Cellular and humoral hypersensitivity to adrenal antigen in experimental adrenalitis

A role for specific cellular, as well as humoral immunity has been suggested in experimental adrenalitis. This study was performed to seek a correlation between cellular and humoral immunity in experimental adrenalitis of the guinea pig. 34 guinea pigs (GP) were arranged into 4 experimental groups. One group (11 GP) was immunized with a single injection of 250 mg homologous adrenal antigen (HAA) in complete Freund's adjuvant (CFA). A second group (6 GP) was similarly immunized at 1 and 14 days. A third group (9 GP) received 3 such injections at 1, 14, and 21 days. The fourth group (8 control GP) received RPMI-1640 in CFA. The following were performed on all groups 10 days after the last injection: lymphocyte response to PHA and HAA; HAA-specific macrophage migration inhibition (MIF); antibody titers to HAA by hemagglutination; and histopathology of adrenal, thyroid and testis. Antibody titers reached a mean level of 500 in each of the 3 HAA-immunized groups. In the single injection group, MIF activity and response to PHA were significantly increased when compared to the other immunized groups and to controls. Histopathologic changes were seen in adrenal glands of all immunized groups, but were most remarkable in the single injection group. Progressively fewer changes were observed in double and triple immunized groups. Antibody titers and histological changes were not found in controls. Histopathology correlated better with cell-mediated immune parameters than with specific antibody titers; this suggests that cell-mediated mechanisms may be the more important factor in pathologic lesions of experimental adrenalitis.