T-cell depletion by monoclonal antibodies does not prevent granuloma formation in mice

Effects of T-cell depletion on the formation of organized granulomas in mouse skin were investigated. Monoclonal antibodies (MoAbs) to L3T4 and Lyt-2.2 were injected into euthymic BALB/c mice in order to deplete both T-helper and T-suppressor cell populations. Four days after injection, hepatic schistosome egg granulomas were transplanted into the skin. Injection of MoAbs to L3T4 and Lyt-2.2 was repeated in the recipient mice 6 days later. At the time of transplantation, flow cytometric analysis showed that the number of T cells which were positively stained with surface markers decreased on average by 68% in both regional lymph nodes and spleen. The mitogen response of spleen cells was also markedly reduced. Despite their immunosuppressed condition, development of organized granulomas was observed in the skin of recipient mice by light and electron microscopy 3 weeks after transplantation. The findings indicate that T-cell function may not be essential for initiation of organized granuloma formation.