Effect of blood transfusions on immune function. Part VI. Effect on immunologic response to tumor.

Transfusions are reported to increase the incidence of tumor metastasis in clinical studies and primary tumor growth in animal studies. We evaluated the effect of transfusions on immunologic response to primary and metastatic tumors in multiple rat models. One half of the animals were administered lactated Ringer's solution and one half ACI rat blood at the time of tumor challenge. In 80 rats a slow-growing colon tumor was implanted subcutaneously. At 4 months there were no significant differences in tumor size or leukocyte infiltration of the tumor. Similar results were obtained with a rapidly growing colon cancer. Analysis of T-lymphocyte subpopulations in both groups showed no differences. Rats transfused at the time of intravenous challenge with a suspension of 1 x 10(6) tumor cells had a mean survival time of 38.3 +/- 0.8 days and the control group had a mean survival time of 41.1 +/- 0.8 days (p = 0.016). One week after transfusion, natural killer cell lysis of tumor cells at a 100:1 effector/target cell ratio was 18.0% +/- 1.8% in the transfusion group and 23.0% +/- 1.3% in the control group (p = 0.034). In conclusion, transfusions in multiple rat cancer models did not affect primary tumor growth or the host's immunologic response to it but did significantly impair natural killer cell function and survival with tumor metastases.