Effect of heterologous antilymphoid-cell serum on tumor isografts and viral leukemogenesis.

Rabbit anti-mouse lymphoid-eell serum (ALS) could either facilitate or inhibit the outgrowth of antigenic sarcoma and lymphoma cell grafts in syngencic hosts, depending on the tumorhost combination. In certain cases, the treatment acted in parallel with the response of the preimmunized host leading to a more efficient rejection. In other cases the opposite was true: host response was counteracted and tumor growth facilitated. It was not possible to ascertain any general rules which could allow a prediction of the effect of ALS treatment on antigenic tumor cell grafts. Administration of ALS to mice inoculated with the Moloney virus during the preleukemic period or after the appearance of primary lymphomas was without detectable effect on lym phoma incidence and development.