Evidence for the release of autocrine growth factor(s) by Hodgkin's cell lines

A cell surface glycoprotein (BLA.36) expressed on Hodgkin's cell and also on normal and malignant B lymphocytes, was identified by reaction with a monoclonal antibody. Expression of BLA.36 was detected on Hodgkin's cell lines, as well as B or pre-B cell lines, but was not detectable on other hematopoietic, carcinoma or melanoma cell lines, both by immunoprecipitation of intrinsically labeled cell lines and by immunocytochemical staining methods. Hodgkin's cell lines which were positive for BLA.36 expression were also responsive to a partially purified Hodgkin's cell growth factor(s) (HCGFs). HCGFs was partially purified by concentrating conditioned medium from a Hodgkin's cell line (HDLM-3), followed by ion-exchange chromatography (DE52) and gel filtration on Sephadex G-50. The active fractions yielded protein bands with apparent molecular weights ranging from 16 to 21 kilodaltons on sodium dodecyl sulphate-polyacrylamide gel electrophoresis under both non-reducing or reducing conditions. Hodgkin's cell lines treated with antiBLA.36 antibody were not growth responsive to exogenously added HCGFs. Addition of alpha-interferon (alpha-IFN) to BLA.36-positive Hodgkin's cell lines resulted in down-regulation of BLA.36, accompanied by inhibition of growth. Cell lines treated in this way failed to respond to exogenously added HCGFs, suggesting a requirement for BLA.36 expression in order for HCGFs to exercise its growth-stimulatory effect.