IMMUNOHISTOCHEMICAL ANALYSIS OF IN-VIVO PATTERNS OF EXPRESSION OF CPP32 (CASPASE-3), A CELL-DEATH PROTEASE

The in vivo patterns of CPP32 (Caspase-3) gene expression were determi ned using an immunohistochemical approach and paraffin-embedded normal human tissues. A rabbit polyclonal antiserum was generated against re combinant human CPP32 protein and shown to be specific by immunoblot a nalysis of various human tissues and cell lines, CPP32 immunoreactivit y was selectively found in certain cell types and was typically presen t within the cytosol, although occasional cells also contained nuclear immunostaining. CPP32 immunostaining was easily detected, for example , in epidermal keratinocyes, cartilage chondrocytes, bone osteocytes, heart myocardiocytes, vascular smooth muscle cells, bronchial epitheli um, hepatocytes, thymocytes, plasma cells, renal tubule epithelium, sp ermatogonia, prostatic secretory epithelial cells, uterine endometrium and myometrium, mammary ductal epithelial cells, and the gastrointest inal epithelium of the stomach, intestine, and colon. In contrast, lit tle or no CPP32 immunoreactivity was observed in endothelial cells, al veolar pneumocytes, kidney glomeruli, mammary myoepithelial cells, Sch wann cells, and most types of brain and spinal cord neurons. Consisten t with a role for CPP32 in apoptotic cell death, clear differences in the relative intensity of CPP32 immunostaining were noted in some shor ter-lived types of cells compared to longer-lived, including (a) germi nal center (high) versus mantle zone (low) B lymphocytes within the se condary follicles of lymph nodes, spleen, and tonsils; (b) mature neut rophils (high) versus myeloid progenitor cells (low) in bone marrow; ( c) corpus luteal cells (high) versus follicular granulosa cells (low) in the ovary; and (d) prostate secretory epithelial cells (high) versu s basal cells (low). These findings establish for the first time the c ell type- and differentiation-specific patterns of expression of an in terleukin-1 beta converting enzyme/CED-3 (Caspase) family protease.