BOTH IFN-GAMMA AND IL-4 INDUCE MHC CLASS-II EXPRESSION AT THE SURFACEOF MOUSE PRO-B CELLS

Pro-B cells are early B-cell progenitors that retain macrophage potent ial. We have studied MHC class II molecules and invariant chain induci bility on four class II negative mouse pro-B-cell clones, We analyzed the effects of IL-4 and IFN-gamma, which represent the major inducers of class II in the B-lymphoid and monocytic/macrophage lineages, respe ctively. After 48 h of treatment with either cytokine, three pro-B-cel l clones (C2.13, A1.5, and F2.2) expressed intracellular invariant cha in and cell-surface class II molecules. One clone (D2.1) remained nega tive. As already reported, more differentiated 70Z/3 pre-B cells were inducible by IL-4 only. These data suggest that the induction of class II and invariant-chain genes are subject to regulation throughout B-c ell differentiation.