STIMULATION OF IGM PRODUCTION IN HUMAN HUMAN HYBRIDOMA HB4C5 CELLS AND HUMAN-LYMPHOCYTES BY SOYBEAN HULL HEMICELLULOSE

We screened immunoglobulin production stimulating factor (IPSF) in several types of dietary fibers using human-human hybridoma HB4C5 cells cultured in a serum-free medium. Among the fibers, soybean hull hemicellulose (SHH) showed the strongest IPSF activity; 1 mg/mL of SHH stimulated IgM production approximately 4-fold. SHH stimulated IgM production of human-human hybridomas derived from fusion partner NAT-30 cells and mouse-mouse hybridomas derived from P3U1 but not as much as those of human-human hybridomas derived from HO-323 cells. When the SHH preparation was fractionated on a Sepharose CL-4B gel filtration column, IPSF activity was observed in a carbohydrate peak at MW 32 000 containing small amounts of protein. The IPSF activity of SHH was reduced by heating at 100-degrees-C and by digestion with trypsin or beta-galactosidase. These results suggested that the IPSF activity of SHH was dependent on both polysaccharide and protein components. SHH also stimulated IgM production of human lymph node lymphocytes but not their IgG and IgE productions.