Table 2. Only phagocytic secrete peptides that load MHC class I molecules.

	Kb expression on RMA-S
Co-culture	I	Y3	Y3–I
RMA-S	2·28	18·04	15·76
RMA-S + l929	3·4	13·02	9·62
RMA-S + infected L929	3·05	14·14	11·09
RMA-S peritoneal macrophages	4·15	33·19	29·04
RMA-S + infected peritoneal macrophages	3·89	45·35	41·46
RMA-S + J774	2·95	48·2	45·25
RMA-S + infected J774	2·67	66·31	63·64
RMA-S	7·98	30·59	22·61
RMA-S + A20	9·41	29·08	19·67
RMA-S + infected A20	4·13	28·94	24·81

Results are shown as the mean fluorescence channel. Co-cultures were performed as described in Fig. 1. L929, peritoneal macrophages from BALB/c mice, J774 and A20 were treated with IFN-γ for 48 hr and infected with Salmonella typhimurium at ratio of 100 bacteria per cell. I, isotype control antibody; Y3, antibody against K^b molecules.