IMMUNOSUPPRESSIVE EFFECTS OF ADAMANTOYL CYTARABINE .I. INHIBITION OF HEMAGGLUTININ FORMATION AND GRAFT VERSUS HOST REACTIONS IN MICE

The immunosuppressive effects of adamantoyl cytarabine [1-β-D-arabinofuranosylcytosine-5′-(1-adamantanecarboxylate); AdOCA] have been examined and compared with the parent compound, cytarabine, in two mouse immunologie systems: the hemagglutinin response to sheep erythrocytes, and the graft versus host reaction. Previous reports by the authors have shown that cytarabine effects were of short duration and that multiple daily injections were necessary for maximum immunosuppression. In contrast, AdOCA demonstrated long-lasting imrnunosuppressive effects after one injection. Data accumulated in other experiments clearly demonstrate the greater immunosuppressive activity of AdOCA compared with cytarabine. This was true irrespective of the basis of comparison (single injections, daily injections, milligram or mole). Further, AdOCA immunosuppression was observed before, during, and after antigenic challenge, whereas cytarabine was shown previously to be most imrnunosuppressive 2 days after antigenic challenge. © 1969.