IMMUNOLOGICAL AND BIOCHEMICAL-CHARACTERIZATION OF BIGLYCAN-LIKE HEMATOPOIETIC FACTOR

Immunological and biochemical characteristics of a 100 000 MW biglycan -like haemopoietic factor, purified from thymic myoid cells 871207B, w ere studied to distinguish them from macrophage colony-stimulating fac tor (M-CSF), which they resemble in activity and biochemical propertie s, Rabbit antibody raised against a synthetic peptide fragment (J-1) d esigned from amino acid sequences specific to the 100 000 MW factor re sponded to 871207B cells, the conditioned medium of 871207B, and capil lary-like structures in the thymus, but not to M-CSF producer L-929 ce lls or the conditioned medium of L-929 cells. In contrast, M-CSF epito pe was detected in L-929 cells and the conditioned medium cells but no t in 871207B cells or the conditioned medium, even after enzymatic dig estion of glycosaminoglycan chains, Treatment of the 100 000 MW factor with chondroitinase ABC and AC produced a 50 000 MW component. Digest ion of this product with N-glycanase resulted in a 40 000 MW protein c omponent. These results suggest that the 100 000 MW factor is a proteo glycan consisting of a core protein with an apparent molecular mass of 40 000 MW, a 50 000 MW chondroitin sulphate chain and 10 000 MW N-lin ked oligosaccharide chains. A small amount of a 40 000 MW monocytic ce ll growth activity was also found in the 871207B cell-conditioned medi um, An enzymatically obtained 40 000 MW factor, the conditioned medium 40 000 MW factor, and the 100 000 MW factor were specifically eluated from an anti-J-1 IgC-immobilized affinity column with monocytic cell growth activity, suggesting that the biological activity resides in th e 40 000 MW core protein. The 100 000 MW factor induced the proliferat ion and differentiation of monocytic lineage cells from a variety of s ources, such as bone marrow cells, peritoneal exudated cells and brain microglia cells.