PHAGOCYTOSIS OF OLD RED BLOOD-CELLS BY MACROPHAGES FROM SYNGENEIC MICE INVITRO

  • 1 January 1977
    • journal article
    • research article
    • Vol. 5  (6) , 480-486
Abstract
The in vitro interaction of peritoneal macrophages with old and young RBC [red blood cells] as well as with enzymatically treated old and young RBC from syngeneic mice was studied. Old RBC were recognized and phagocytized by macrophages, but young RBC were not. Neuraminidase treatment of both young and old RBC had little effect on the extent of phagocytosis. Trypsin treatment markedly reduced the phagocytosis of old RBC and had no effect on the phagocytosis of young RBC. The level of phagocytosis of old RBC by macrophages from mineral-oil treated mouse peritoneal cavities was roughly half that of macrophages from untreated mice. Old RBC may be recognized due to the presence of cytophilic antibodies on the surface of the macrophages. The specificity of these hypothetical cytophilic antibodies is believed to be directed towards sites which are absent or shielded in young RBC, and exposed in old RBC. Trypsin treatment of old RBC appears to remove these antigenic sites from the old RBC. The lower level of phagocytosis of old RBC by mineral-oil induced macrophages could be due to the previous phagocytic activity of these cells, and their relatively uncoated, newly formed plasma membrane, lacking cytophilic antibodies. In support of this hypothesis, it was demonstrated that trypsin treatment of macrophages resulted in a markedly decreased phagocytosis of old RBC.