Augmentation of Hybridoma Growth and Its Monoclonal Antibody Production by Supplementation with Thymus Extracts

Effects of thymus extracts on growth of mouse hybridoma and its production of monoclonal antibody (Mab) against human serum albumin were investigated. Water extracts of calf thymus were fractionated into high- and low-molecular weight fractions (HM and LM, respectively) by ultrafiltration through a Millipore membrane filter with nominal molecular weight limit of 5000. The Mab production was increased about 10 times by supplementation of serum-free basal medium with HM at a concentration equivalent to 0.5% calf thymus. The increases of Mab titers paralleled with those of cell counts. Trypsin-digested HM showed least capacities in promoting the hybridoma growth and its Mab production. DEAE-HM, a fraction made free of basic proteins from HM by DEAE-cellulose chromatography, showed capacities similar to those observed with HM. Electrophoretic analysis revealed that DEAE-HM was composed of a number of proteinaceous components with molecular sizes of 25 to 30 kDa and pIs ranging from neutral to acid.