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, Ia^k, 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.