Both IFN-γ and IL-4 Induce MHC Class II Expression at the Surface of Mouse Pro-B Cells

Pro-B cells are early B-cell progenitors that retain macrophage potential. We have studiedMHC class II molecules and invariant chain inducibility on four class II negative mouse pro-B-cell clones. We analyzed the effects of IL-4 and IFN-γ, which represent the major inducersof class II in the B-lymphoid and monocytic/macrophage lineages, respectively. After 48 h oftreatment with either cytokine, three pro-B-cell clones (C2.13, A1.5, and F2.2) expressed intracellularinvariant chain and cell-surface class II molecules. One clone (D2.1) remained negative.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 regulationthroughout B-cell differentiation.