Cardiopulmonary bypass and host defense functions in human beings: I. Serum levels and role of immunoglobulins and complement in phagocytosis.

In patients undergoing open-heart surgical procedures, the serum levels of immunoglobulins and complement were determined as well as the functional capacity of these defense proteins as opsonins to facilitate phagocytosis by polymorphonuclear leukocytes. A considerable decrease in serum levels of the proteins studied was found after cardiopulmonary bypass (CPB). As a result, the opsonic capacity of post-CPB plasma was diminished. After correction for hemodilution, however, no difference between pre- and post-CPB plasma, as measured by the activity of thermolabile (e.g., complement C3) and thermostabile (e.g., immunoglobulin IgG) opsonins, could be demonstrated. It is concluded that CPB causes a quantitative but no functional decrease in levels of IgG and C3.