EXPRESSION OF FUNCTIONAL MHC CLASS-II MOLECULES BY A MOUSE PRO-B CELLCLONE

We describe here the G12 pro-B cell clone that has been isolated from an IL-7 transgenic mouse. This clone has the phenotype B220(+),BP-1(+) ,HSA(+),CD43(+),lambda 5(+) and CD25(-), and has its Ig locus in a ger mline configuration. G12 cells spontaneously express cell-surface MHC class II molecules, although to a much lesser extent than the nature M 12.4.1 B-cell lymphoma. G12 cells can process and present the native H en Egg Lysozyme (HEL) to an MHC class II-restricted T-cell hybridoma. The efficiency of presentation is inferior to that obtained with M12.4 .1 cells. This is the first report where a pro-B cell can serve as APC in an MHC class II-restricted presentation.