T-cell immunodeficiency induced by T-cell mitogens combined with cyclophosphamide injection

In the murine system in vivo administration of several T-cell mitogens (LcA, Con A, anti-Thy 1.2 mAb) followed by cyclophosphamide (CP) inhibited the functional activity of T-cell subsets (Th1, Th2, Ts) but not that of B cells. T-cell counts in the spleen of treated mice proved to be significantly decreased. Conversely, T mitogens or CP alone produced a negligible effect if any. Adoptively transferred thymocytes from intact donors restored T-dependent splenocyte responses in experimental mice. In addition, it did not suppress the normal response to sheep red blood cells (SRBC). Our results indicated that the acquired immune deficiency under study is caused by polyclonal elimination (deletion) of mitogen-stimulated T cells, and could be regarded as a model of CP-induced tolerance.