The Journal of Immunology, 2007, 178: 93.22.
Copyright © 2007 by The American Association of Immunologists, Inc.
Partial MHC Class II molecules preferentially bind to B cells
Jason M Link1,
Roberto Meza-Romero2,
Michael Afentoulis1,
Marisa Agotsch2,
Dorian LaTocha1,
Gregory Burrows2 and
Arthur A Vandenbark1,2
1 Portland Veterans Affairs Medical Center, 3710 SW U.S. Veterans Hospital Road, Portland, OR, 97239,
2 Neurology, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Rd., Portland, OR, 97239
Abstract
Recombinant, two-domain MHC Class II proteins (
1
1MHCII) that lack sequence from the membrane proximal 2 and 2 domains of MHC Class II adhere preferentially to B cells in vivo and ex vivo; whereas, full length (four-domain) constructs do not bind. Because 11MHCII molecules that contain only native MHC Class II sequence have preferential affinity for B cells, we hypothesize that a natural, cell-free form of MHC Class II (similar to recombinant 11MHCII) exists and has affinity for a receptor expressed by B cells. Evidence that endogenous, natural MHC Class II molecules transfer to B cells and that 11MHCII has inter- and intra-species affinity for B cells suggest that this is a natural and evolutionarily conserved property. And evidence that 11MHCII can stimulate CD4+ T cells suggests that there is an immune function for partial, cell-free MHC Class II. Transfer of immunoreactive, cell-free 11MHCII/Ag complexes to B cells suggests a here-to-fore unrecognized pathway for T cell activation.
