Purification and characterization of a Hodgkin's and B cell-associated glycoprotein

A glycoprotein (BLA.36) expressed on the plasma membrane of Hodgkin's cells and also on normal and malignant B lymphocytes and histiocytes, was identi fied by reaction with a monoclonal antibody. BLA.36 was not detectable on o ther hematopoietic, carcinoma or melanoma cell lines. BLA.36 was purfied to homogeneity by extracting proteins from a Hodgkin's cell line (HDLM-3) fol lowed by immunoaffinity chromatography, utilizing immobilized anti-BLA.36 a ntibody, and gel filtration on Sephacryl S-100 in the presence of protein d issociating agents. The purified component yielded a single band on sodium dodecyl sulphate/polyacrylamide gel electrophoresis under both non-reducing and reducing conditions, and closely related thr ee isotypes of similar mo lecular weight and with the apparent isoelectric points that ranged from 5. 0 to 5.2 on two-dimensional gel electrophoresis. The purified BLA.36 reacte d with the original specific antibody, on both one or two-dimensional gel e lectrophoresis, suggesting that antigenic determinant was not adversely aff ected during purification procedure. Competitive immunoprecipitation analys es and the determination of N-terminus sequence of the first 13 amino acid residues suggest that BLA.36 is unrelated to other known Hodgkin's or hemat opoietic cell antigens. Finally, significance of BLA.36 expression on the g rowth of BLA.36-positive cell lines was studied Blocking of BLA.36 with ant i-BLA.36 antibody led to the in vitro growth-inhibition of BLA.36-positive cell lines. The antibody pre-absorbed with the purified BLA.36 was unable t o exert growth-inhibition, demonstrating the specificity of reaction. In ad dition the treatment of the BLA.36-positive cell lines with differentiation -inducing agent, alpha-interferon (alpha-IFN) down-regulated BLA.36 express ion and also showed in vitro growth-inhibition of BLA.36-positive cell line s. Taken together; these results suggest a growth-related function of BLA.3 6.