Suppression of murine NK activity induced by Corynebacterium parvum: further characterization and abrogation of suppressor cells

Formalin-killed Corynebacterium parvum (CP), given at a dose of 0.4-0.7 mg/mouse IV or IP, induced suppressor cells for NK activity in B6C3F1 mice. The suppressor cells belong to at least two different populations, plastic adherent and nonadherent, and were not depleted by antibodies specific for Thy-1.2, Iak, or NK-1.2 surface markers. Administration of p-I:C, an interferon-inducer, to animals 18 h before the assay did not affect the suppressor activity. Hypotonic shock treatment of splenocytes abrogated the in vitro suppressive activity, and subsequent reconstitution of the shock-treated cells with RBC failed to restore the suppressive activity. SJL/J mice, which have low NK activity, exhibited suppressor activity comparable to B6C3F1 mice following CP treatment, whereas CP-treated BALB/c athymic and euthymic mice showed a lower ability to generate suppressors for NK as compared to B6C3F1 mice.