What does the complement receptor type 1 do?

CR1: There is some controversy here, but it seems to mainly act through binding of C1q upon forming complexes with antibody in the bloodstream. CR1 is highly expressed on red blood cells, so these cells carry immune complexes away from the site of attachment to the spleen where the immune complexes are destroyed. An "immune complex" is a cluster of antibodies and there antigen targets (like a virus).