[Study on the induction of immunological suppression by blood transfusion]

There have been several reports that suggest the possibility that blood transfusion induces the suppression of immunity. For the purpose of studying immunological effect of blood transfusions, in vivo and in vitro experiments were performed. Using C3H/He (H-2k), DBA/2 (H-d), C57BL/6 (H-2b) and BDF1 (H-2b,d) mice, blood transfusions were done each other. In in vitro experiment, the effect of blood transfusion was examined with the survival of allogenic tumor, Meth-A (H-2d), transplanted in C3H/He (H-2k). And in in vitro experiment, natural Killer activity and CTL activity were investigated following blood transfusions. These experiments led to the following results: Some allogenic blood transfusions enhanced allogenic tumor survival. Only leucocytes transfusion showed such effects. The effective factor existed in the transfused serum. NK activity was suppressed by blood transfusion. CTL activity was not correlated with blood transfusion. From these results, it was concluded that allogenic blood transfusion could cause immunosuppression, especially suppression of NK activity and it was considered that clinical blood transfusion can also result in a tendency towards acceleration of tumor growth in the cancer-carrying body.