CD46, a complement regulatory protein/measles virus receptor, and its relation to hematological disorders.

During measles virus (MV) infection, lymphopenia and immune suppression are observed in humans, yet the mechanisms underlying these effects remain unknown except that membrane cofactor protein (MCP, CD46) acts as a receptor for MV, accelerating entry of the virus into host cells. CD46 is a complement regulator, the role of which is to protect host cells from the autologous complement system. Thus, it encompasses complement-related and MV-mediated immune modulation. In this review, I discuss the structural and functional differences between CD46 on lymphocytes and on granulocytes, which partly explain the higher susceptibility of lymphocytes to MV than other blood cells to clarify the mechanisms of MV-mediated lymphopenia and immune suppression, and help resolve the T cell immunity dysfunction secondary to virus infection including HIV.