The role of mononuclear phagocytes in cardiac allograft rejection in the rat: III. The effect of cells extracted from rat cardiac allografts upon beating heart cell cultures

Abstract

Cells extracted from rat cardiac allografts were able to bring about cessation of beating of heart cell culture monolayers nonspecifically. Nonadherent populations, depleted of macrophages, were consistently less potent than unseparated cells in this assay. Cells extracted from isografts were totally ineffective. Allogeneically stimulated peritoneal cells were also nonspecifically active. Again, nonadherent cells were less efficient than unseparated cells at stopping heart cell monolayers from beating, while adherent cells, enriched for macrophages, were more efficient. Activated bone marrow culture macrophages syngeneic or allogeneic to the heart cultures were also highly potent in beating heart cell assays. Thus in all cases the predominant effector cell type was adherent and nonspecific in its action and therefore presumably a macrophage. Supernatants from wells in which no beating cells remained following incubation with each type of effector population tested were transferred undiluted to fresh wells. In all cases there was no effect at all upon the beating of heart cell monolayers. Antirat heart antiserum plus complement was able to bring about the cessation of beating of heart culture monolayers at a dilution of 1:64. Alloantibody plus complement did not bring about cessation of beating at any dilution, although nonmyocardial cells were killed. The possibility that macrophages are the chief effector cell type in a DTH-like mechanism for cardiac allograft rejection is discussed.