The Immunosuppressive effects of prostaglandin E₁ (PGE₁) used in cardiopulmonary bypass (CPB) operation were studied. We examined 30 patients, with ischemic heart diseases. The patients were divided into 3 groups: 11 patients given PGE₁ in group PG (G-PG), 10 patients given amurinon, a phosphodiesterase inhibiter, in group A (G-A), and 9 patients not given either of those drugs in the control group (G-C). Immunologically, lymphocyte subpopulations, and adhesion molecule expression on cell membrane and phagocytosis of neutrophils were analyzed before, at the time of, and after the operation until POD 7. The prominent effects of PGE₁ were observed on neutrophils. The expression of CD 62L, an adhesion molecule designated as L-selectin, on the cell surface membrane of neutrophils significantly increased during and after CPB in G-A and G-C, but it remained unchanged in G-PG during the observation period. Moreover, CPB caused an enhancement of the phagocytic activity of neutrophils in all groups, but its degree was much less in G-PG than in the other two groups. Among lymphocyte subpopulations, the number of CD 3⁺T-cells in G-PG rather than that of CD 20⁺B-cells reduced more greatly than those values observed in G-A and G-C. The decrease of T-cell number, throughout the observation period, in G-PG seemed to be mainly due to the decrease of the number of CD 4⁺T-cells designated as helper T-cells, although the number of CD 8⁺T-cells esignated as killer/suppressor T-cells slightly decreased on PODs 3 and 7. Amurinon, as a whole, did not exert any significant effect either on lymphocytes or on neutrophils in our experiments. Taken together, these results show that the treatment of patients with PGE₁ during CPB causes suppressive effects on immunorelevant cells. It may mitigate the activity of neutrophils, which are suspected as a possible culprit causing reperfusion injury. However, these suppressive effects, including the lowered numbers of CD 4⁺T-cells, may render the patients more vulnerable to infection. Much more intensive cares is required in these patients after operations.

A 65-year-old man had undergone coronary artery bypass grafting (CABG) using a left internal mammary artery graft 3 years and 5 months previously. Anginal pains recurred due to an occlusion of the left subclavian artery. A subclavian-subclavian artery bypass was performed using 8mm e-PTFE graft with rings and the results were excellent. This grafting procedure appears to be a safe and satisfactory reperfusion technique, and therefore we recommend its use in patients requiring CABG.