Inhibition of Lymphoma Growth in the Spleen and Liver of Lethally Irradiated Mice

Abstract

The growth of murine lymphomas carrying the H-2^d (LSTRA, P388), the H-2^k (6C3HED), and the H-2^a (LAF-17) haplotypes was studied in spleen and liver of lethally irradiated (850 to 1000 R) compatible or allogeneic mice, with the ¹²⁵I-5-iodo-2′-deoxy-uridine uptake method. According to the genetic pattern of the Hh (hemopoietic-histocompatibility) system, recipient hosts were either susceptible or resistant to bone marrow graft carrying the same haplotypes as those of the lymphomas studied. The results showed that the tumor cell growth was impaired in the spleen of irradiated Hh-incompatible resistant hosts (e.g., P388 into B10, B10.BR and CBA), suggesting that lymphoma and bone marrow cells could share common Hh antigens. However, inhibition of lymphoma growth occurred also in the spleen of irradiated Hh-susceptible mice, either Hh-compatible (e.g., P388 into B10.D2; 6C3HED into AKR or CBA) or Hh-incompatible, but genetically unable to respond against bone marrow cells (e.g., LSTRA or P388 into C3H, or 6C3HED into BALB/c or SJL). In almost all cases growth inhibition was absent or weak in the liver. These results suggest that lymphoma cells could express antigens not detectable on normal bone marrow cells, capable of eliciting radioresistant inhibition of tumors (RIT) predominantly in the spleen of mice susceptible to marrow graft of the same genetic origin as that of the lymphoma tested. At the present time no direct data are available to determine whether natural cytotoxicity would play a role in RIT responses.