Brief Definitive Report A Novel Anti-Vpre-B Antibody Identifies Immunoglobulin-Surrogate Receptors on the Surface of Human Pro-B Cells

Vpre-B and k5 genes, respectively, encode V-like and C-like domains of a surrogate immunoglobulin light chain (~L). Such WL complex is expressed in early progenitor B (pro-B) cells, before conventional immunoglobulin heavy (/~H) and light (L) chains are produced. We raised a wide panel of monoclonal antibodies (mAbs) against soluble recombinant Vpre-B proteins to study early events in httman B cell development. One of these antibodies, B-MAD688, labeled surrogate Ig-complexes on the surface of btHpro-B cell lines and normal bone marrow cells in immunofluorescence assays. Immunoprecipitations using surface-labeled pro-B cells and B-MAD688 mAb indicated that human ~ L is associated with high molecular weight components homologous to the surrogate heavy (~H) chains described in mouse. Using B-MAD688 and SLC2 mAbs, we were able to distinguish between XltH~L and btHWL complexes on the surface of human pro-B and later precursor, pre-B, cells. The finding of ~ H ~ L complexes in mouse and man lead us to hypothesize a role for ~H-containing receptors in B cell development.