Progression of the immune response to solubilized tumor antigens

Local adoptive transfer assays (LATA) were used to analyze and compare the progression of the immune response in C3H/HeJ mice to irradiated tumor cell vaccine and to crude 3M KCl solubilized antigens extracted from a syngeneic methylcholanthrene-induced fibrosarcoma. Sequential LATA performed 2, 6, 9, 12 and 15 days after soluble antigen pretreatment of spleen cell donors revealed a sinusoidal evolution of lymphoid cell activity. An initial brief period of potent tumor facilitation (days 6-9) was followed by a phase of tumor neutralization (days 9-12) which decayed by day 15. On the other hand, spleen cells from donors sensitized with irradiated tumor cells exhibited consistent tumor neutralization which was sustained throughout 15 days. Thus the tumor growth facilitation observed only in CSA-treated donors may represent a qualitative difference in the immune state induced by soluble, as opposed to cellular, forms of tumor antigen.