These data demonstrate that blockade of ICAM-1/LFA-1 binding at the time of allorecognition potently blocks initial T cell effector functions that could be due to lack of effective T cell/APC engagement.
A monoclonal antibody (MAb), KuN241, recognized an antigen present on all monocytes, polymorphonuclear leukocytes (PMNs), B cells, and a subpopulation of T cells. Cell surface expression pattern and immunoprecipitation studies indicated the molecule recognized by KuN241 to be complement receptor 1 (CR1). This was confirmed by sequential immunoprecipitation using E11, a CR1-specific monoclonal, and by immunoprecipitation analysis of a truncated transfection product of CR1. In vivo activation of PBLs for 7 days with pokeweed mitogen (PWM) abrogated surface expression of CR1 on B cells. Overnight culture with phorbol 12-myristate 13-acetate (PMA) downregulated the expression of CR1 detected by KuN241 both on PMNs and monocytes. Addition of MAb KuN241 to purified PMN and monocytes resulted in a transient increase in intracellular calcium ([Ca2+]i). This was blocked by the Fab fragment of MAb KuFc79 directed against the Fc gamma receptor. Further, Fab fragment of KuN241 cross-linked with F(ab')2 goat anti-mouse Ig failed to increase [Ca2+]i levels. Taken together, these results suggested a novel mechanism for transmembrane signaling events by dual binding of KuN241, the Fab region to CR1 and the Fc region of Fc gamma RII.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.