Figure 5.
The cecal bacterial lysate component that stimulates C3H/ HeJBir CD4+ T cells is a protein. APCs from C3H/HeJ mice were pulsed with cecal bacterial antigens from C3H/HeJ mice that had been pretreated with trypsin and then dialyzed, or dialyzed but not trypsin-treated, or stored in a tube for an equivalent amount of time. Control APCs were pulsed overnight with freshly obtained cecal bacterial antigens. Each of these antigen-pulsed APCs was added to aliquots of the same pool of C3H/HeJBir CD4+ T cells and cultured as described in the legend to Fig. 1. 0.5 μCi of [3H]TdR was added to the wells for the last 18 h of a 5-d culture. Results are expressed as mean cpm ± SD of triplicate cultures and are representative of three experiments.