Presence of a-2-Macroglobulin in Normal but not in Malignant Cervical Epithelium1

o-2-Macroglobulin («2M)was demonstrated in normal and mildly dysplastic cervical epithelium using immunohistochemical methods. In contrast, staining for «2Mdiminished gradually with advancing epithelial dysplasia and was totally negative in truly neoplastic lesions. No in vitro synthesis could be detected in cultured ectocervical cells or in a corresponding malignant cell line (HeLa). However, «2Mwas taken up from added human serum by cultured normal ectocervical cells, whereas HeLa cells remained negative also under these conditions. These and pre vious results suggest that normal cells may have the capacity to synthesize or endocytose «2M,thus possibly regulating their pericellular proteolysis, while these functions may be defective in malignantly transformed cells.