Influence of T-helper cell specific monoclonal antibody on progressive growth of B-cell lymphomas in SJL/J mice: correlation of acute treatment dosage with tumor dormancy or complete remission in long-term survivors.

Transplantable follicular center cell lymphomas of SJL/J mice (SJL/FCC) are B-cell-derived tumors that stimulate host T-helper (TH) cells and grow progressively in the lymphoid tissues of immunocompetent, syngeneic recipients. The host TH cells that respond to the I-As determinants on SJL/FCC lymphoma cells produce a variety of lymphokines, some of which (e.g., IL-5) promote in vitro tumor growth. The results presented here demonstrate that removal of the cellular source of tumor growth-promoting lymphokines by treatment of lymphoma-injected mice with TH cell specific monoclonal antibodies (anti-L3T4a) inhibits progressive tumor growth and prolongs survival significantly. However, long-term survival is mediated by different mechanisms, depending on the dosage of L3T4a mAb used. Tumor cells are present, but dormant, in mice that receive low-dose (less than 200 micrograms/injection) treatment. In contrast, tumor cells are undetectable in mice that receive high dose (1200 micrograms/injection) treatment.