EXPRESSION OF APOGENS AND ENGULFENS DURING PROGRAMMED CELL-DEATH IN THE NERVOUS-SYSTEM OF THE CHICK-EMBRYO

Two categories of cell death related to antigens, apogens and engulfen s, have been reported to be expressed by apoptotic cells and the cells involved in their engulfment in the immune system, and in mesenchymal tissue in the limb of the chick embryo (ROTTELLO et al., 1994). To de termine whether these antigens are also expressed during the process o f neuronal death, the distribution of immunoreactivity to both anti-ap ogen and anti-engulfen antibodies was examined in the spinal cord and the dorsal root ganglia of the chick embryo. Anti-apogen antibodies la beled a sub-population of the profiles of dying cells in regions where cell death was occurring. The extent of labeling by anti-apogens vari ed from 3% to 70% of the total number of dying profiles depending on t he specific antibody used and the neuronal region examined. Immunoreac tive labeling by the anti-engulfen antibodies mainly involved large ce lls that contained debris of dead cells. These results indicate that a t least some dying neuronal cells express common antigens that are sha red by dying mesenchymal cells during programmed cell death, and that phagocytotic cells of the immune system are involved in the engulfment of neuronal cells that have undergone programmed cell death.