sentences:  In human mononuclear phagocytes, phagocytosis of "Mycobacterium tuberculosis" is mediated in part by human monocyte complement receptors including CR3.CR3 has also been shown to mediate phagocytosis of the Lyme disease causing bacterium, "Borrelia burgdorferi", in the absence of iC3b opsonization.CR3 and CR4, both members of the β2-integrin family, are generally thought to exhibit overlapping functions in myeloid cells and certain lymphoid populations.