A sharp antigen-induced increase in the number of cells secreting non-specific immunoglobulins in vitro

The cultivation of normal mouse spleen cells in a modified Mishell-Dutton system for 1-4 days in the presence of a water-soluble antigen of sheep red blood cells results in a sharp increase in the number of cells secreting non-specific immunoglobulins (nIFC). This increase is much more visible if spleen cells from mice primed with the same antigen 3-4 days before cultivation, are used. The rise in NIFC becomes apparent on day 1 and runs up to maximum on day 3. At this time a peak of 165 X 10(3) nIFC per 10(6) cells is attained, i.e. the nIFC quantity reaches approximately 33% of total B-cells. Kinetics of the antibody-forming cells and nIFC appearance under varying conditions is different. Clearcut differences are also revealed between the mechanisms of regulation of both these populations. The initial population of cells destined to form non-specific immunoglobulin is estimated to be 363/10(6) cells during a primary immune response in vitro; if splenocyte donors are primed with a homologous antigen, this population become approximately 800-1,900/10(6) cells.