The destruction of red cells by antibodies in man. III. Quantitative factors influencing the patterns of hemolysis in vivo.

During the past several years it has become apparent through experimental studies with Cr51-labeled red cells that injured red cells are removed from the circulation in either of two general ways. In the first, altered red cells are selectively trapped in the spleen. Such splenic trapping can be induced by coating the cell surface with adherent proteins, as with incomplete agglutinins (1, 2) or metallo-protein complexes (1, 3), or by increasing red cell thickness, as when red cells are made spherocytic by exposure to heat (4) or to lecithin (5). In addition, immature red cells (6, 7) and red cells injured by "oxidant" drugs, such as acetylphenylhydrazine (5, 8) are preferentially, although not so avidly, sequestered by the normal spleen. When relatively small amounts of Cr51-labeled red cells are injected into man and the splenic filter remains "unsaturated," red cells coated by incomplete antibodies or rendered spherocytic in vitro are removed from the circulation by the spleen at a constant rate of approximately 3 + 1 per cent per minute (2, 9), a rate which probably approaches the splenic blood flow.' In some instances red cells so trapped in the spleen may be released subsequently into the circulation (5).