OPTIMIZING PRODUCTION OF HUMAN MONOCLONAL IGG ANTIBODIES BY IN VITRO-PRIMED HUMAN PBMC - INFLUENCE OF CD56(+) NK CELL DEPLETION

Freshly isolated human peripheral blood mononuclear cells (PBMC) were immunomagnetically depleted of CD56(+) cells, When these CD56(-) PBMC populations were cultured in the presence of autologous donor serum, p olyclonal activation with IL-2 and pokeweed mitogen (PWM) generally re sulted in exclusive production of IgG antibodies. Fusion with SP2/O-Ag 14 mouse myeloma cells was highly efficient and yielded a great number of IgG-producing heterohybridomas, These conditions were used for in vitro immunization with viable human HT29 tumor cells, After fusion, a n increase in hybridoma clones producing IgG monoclonal antibodies (MA b) with HT29 specificity showing a higher portion of MAb binding to th e surface of viable HT29 cells was recorded, This immunizing efficienc y was not observed with HT29 membrane protein fractions or HT29 protei ns integrated into ISCOM particles, Investigations with human anti-a G al antibodies showed that the IgG antibodies produced by the human/mou se heterohybridomas did not contain the mouse-specific Gal alpha 1-3Ga l epitope.