DEPRESSED T-CELL REACTIVITY AND SUPPRESSOR ACTIVITY OF LYMPHOID-CELLS FROM CYCLOPHOSPHAMIDE-TREATED MICE

The in vitro proliferative activity of thymus-derived (T) lymphoid cells from cyclophosphamide-treated mice (Cy-mice), and the relationship between this and some in vivo immunological responses was studied. The proliferative response to phytohemagglutinin (PHA) and allogeneic cells was depressed for up to 3 wk after drug treatment in spleen and lymph node cells, responsiveness recovering more rapidly in lymph node cells. Cell concentration in culture was important in such measurements as cells from some Cy-mice were able to inhibit their own proliferation and that of normal lymph node cells. No stable soluble factor responsible for this effect could be isolated. In vitro proliferative activity is not a good indicator of in vivo T-cell as indicated by the rapid recovery of ability to reject skin grafts and the fairly rapid recovery of ability to produce cytotoxic cells compared to the slower recovery of in vitro T-cell activities.