Description: The 8E2 monoclonal antibody reacts with human CD46 (membrane cofactor protein). CD46 is a transmembrane glycoprotein consisting of four regularly expressed isoforms, giving an electrophoretic profile of two heterogeneous protein species of 51-58 kDa ("lower band") and 59-68 kDa ("upper band"). CD46 is expressed on the majority of nucleated cells, and functions as a regulator of complement function by binding complement components C3b and C4b, which serves to protect the host from autologous complement attack. CD46 has been called a "pathogen magnet" as it is known to play a role in the entry of several pathogens including strains of measles virus, human herpes virus type 6, group A streptococci and Neisseria.
Cross-linking TCR on naïve human peripheral blood CD4+ T cells together with CD46, rather than CD28, induces more robust proliferation than achieved with stimulation by the costimulatory molecule CD28, as well as other qualitative differences. There is evidence to suggest that stimulation of TCR and CD46 activates natural CD4+CD25+ T regs, which are non-proliferating, but produce high amounts of granzyme A, and kill activated CD4+, CD8+, CD14+ monocytes, immature dendritic cells and mature dendritic cells.