In vitro production of gamma interferon is dependent on the mouse genotype.

C57B1/6 and BALB/c mice were compared for their in vitro capacity to produce gamma interferon (IFN-gamma) in response to specific antigen (i.e., Purified Protein Derivative in bacillus Calmette-Guérin sensitized animals) and T-cell mitogen (Concanavalin A). In both cases C57B1/6 spleen cells produced five to ten times more IFN than identically treated BALB/c spleen cells. More detailed analysis of in vitro induced BCG-PPD IFN indicates that the low IFN level in BALB/c cultures is neither caused by classical splenic suppressor cells such as macrophages or T-cells, nor by inactivation of secreted IFN by inhibitory substances.