The Importance of Dosage in the Intradermal Immunization against Transplantable Neoplasms

It has been observed in recent studies (9) that mice ot~ a pure inbred line can be immunized against a tumor that originated in an animal of the same line. The method employed for immunization (3, 4) consists of inoculating intradermally a small dose of tumor cell suspension. In certain instances the resulting intradermal tumors regress spontaneously, and animals that recover are immune to reinoculation with the same neoplasm. In many instances, however, and especially when larger doses of tumor are inoculated, the intradermal tumors do not regress, but grow progressively, and eventually kill their hosts (3, 9). The present studies, a continuation of this previous work, were designed to determine in systematic experinaents whether the hitherto high mortality rate, incident to progressive growth of many of the intradermal tumors, could be substantially reduced by using morc diluted tumor cell suspensions for the purpose of immunization. In addition, experiments were designed to determine the degree of immunity acquired by male and female mice that recovered from the intradermal neoplasms.