Transient decreases in human T cell proliferative responses following vaccinia immunization

To further study the immunosuppression associated with virus infections, we analyzed the proliferative responses of serial PBMC samples obtained follo wing vaccinia virus immunization. In four of five volunteers, responses to PHA, anti-CD3, vaccinia virus, and recall antigens were markedly decreased at at least one time point between days 5 and 29 after vaccination. Respons es to PHA were restored by the addition of IL-2 or irradiated autologous he althy PBMC in the two volunteers tested, suggesting that the proliferation defect is attributable to accessory cell dysfunction. In one donor, immobil ized anti-CD3 failed to induce proliferation, but addition of immobilized a nti-CD28 partially restored proliferation. These results indicate that vacc inia virus infection can transiently suppress proliferative responses of PB MC, in part by causing accessory cell dysfunction. Our findings extend the list of viral infections associated with systemic immunologic effects and d emonstrate that suppression of proliferation can occur with localized virus infections. (C) 2000 Academic Press.