SUPPRESSION OF DELAYED-HYPERSENSITIVITY TO TUBERCULIN BY ANTIGENIC-COMPETITION - A POSITIVE IMMUNOREGULATORY MECHANISM SENSITIVE TO CYCLOPHOSPHAMIDE

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 42  (4) , 549-559
Abstract
Effector mechanisms that produce delayed hypersensitivity [DHT] reactions to tuberculin [TB] are subject to positive immunoregulation. Two different immunoregulatory mechanisms are demonstrated. One is specific and the other, antigenic competition, is nonspecific; both are sensitive to cyclophosphamide (CY). DHT to purified protein derivative (PPD) in guinea pigs can be enhanced by the administration of CY 3 days before but not after immunization. The enhanced response seems to result from the reduced influence on effector cells of CY-sensitive suppressor cells. Passive transfer of DHT to PPD is facilitated by the use of cells from CY treated animals. The response to both immunization and skin testing with ovalbumin in animals immunized with this antigen in Freund''s complete adjuvant produces a marked, nonspecific reduction in the DHT response to PPD. CY given 3 days before or 1 day after immunization prevents this suppression of the PPD response by antigenic competition. Evidently in the generation of both the specific suppressor cells for TB and the nonspecific suppressor cells of antigenic competition, that can influence effector cells for TB, a period of rapid cell proliferation occurs that renders both mechanisms sensitive to CY.