ANTI-APOGENS AND ANTI-ENGULFENS - MONOCLONAL-ANTIBODIES REVEAL SPECIFIC ANTIGENS ON APOPTOTIC AND ENGULFMENT CELLS DURING CHICKEN EMBRYONIC-DEVELOPMENT

We have isolated a group of monoclonal antibodies that specifically re cognize either apoptotic or engulfment cells in the interdigit areas o f chicken hind limb foot plates, and throughout the embryo. Ten of the se antibodies (anti-apogens) detect epitopes on dying cells that coloc alize to areas of programmed cell death, characterized by the presence of apoptotic cells and bodies with typical cellular and nuclear morph ology. Our results indicate that cells destined to die, or that are in the process of dying, express specific antigens that are not detectab le in or on the surface of living cells. The detection of these apopto tic cell antigens in other areas of programmed cell death throughout t he chick embryo indicates that different cell types, which form specif ic tissues and organs, may utilize similar cell death mechanisms. Six of the monoclonal antibodies (anti-engulfens) define a class of engulf ment cells which contain various numbers of apoptotic cells and/or apo ptotic bodies in areas of programmed cell death. The immunostaining pa ttern of the anti-engulfen R15F is similar to that of an antibody agai nst a common leukocyte antigen, suggesting the participation of cells from the immune system in the removal of apoptotic cell debris. These novel monoclonal antibody markers for apoptotic and engulfment cells w ill provide new tools to assist the further understanding of developme ntal programmed cell death in vertebrates.