Factors determining long-term chimerism of lymphoid tissue in cyclophosphamide treated mice

The conditions of origin of long-term chimerism were investigated in adult CBA mice receiving cyclophosphamide and F₁(CBA×C57BL/6) spleen cells. Essential conditions are a high dose of cells (more than 50×10⁶), a dose of cyclophosphamide of not less than 200 mg/kg, and short intervals (3–6 h) between their injections. The results are interpreted from the standpoint of the hypothesis that cyclophosphamide can induce reversible injuries in lymphocyte DNA; these injuries become fixed after contact between lymphocytes and antigen and they lead to death of the corresponding cell alone.Laboratory of Immunologic Tolerance, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. V. Vygodchikov.) Translated from Eyulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 194–197, February, 1976.