The Experimental Immunology Branch flow cytometry laboratory currently supports multiple research projects for more than 40 investigators. These investigations involve multiparametric quantitative single cell analysis of, and electronic cell separation based upon, parameters associated with cells freshly prepared from different species and/or tissues, as well as a spectrum of in vitro cultured cells. Basic research support is provided to members of the EIB and to other investigators within DBS. Currently supported projects include, but are not limited to, the following areas of study: a) in vivo and in vitro analyses of intra-cellular signaling via T cell surface molecules; b) analyses of cellular processes and/or defects in animals with genetic modifications; c) studies of the pathogenesis of graft-versus host disease; d) analyses of the coordinate cell surface expression of cell adhesion molecules; e) investigations of T cell repertoire generation; g) analyses of expression of transplantation antigens; h) investigations of mechanisms involved in antigen presentation processes; and i) analyses of the mechanisms involved in marrow graft rejection versus acceptance.