Macrophages are characterized by the presence of which type of surface receptors?

Macrophages play a crucial role in the immune system and possess a variety of surface receptors that enhance their function. Among these, complement receptors, specifically the C3b complement receptors, enable macrophages to recognize and phagocytize opsonized pathogens. When pathogens are coated with complement proteins like C3b, macrophages can bind to them through these receptors, facilitating enhanced clearance of these pathogens and playing an essential role in the innate immune response.

While CD4 receptors, MHC class II molecules, and immunoglobulin receptors are associated with other immune cells or specific immune functions, they are not the primary characteristic receptors of macrophages. CD4 is predominantly found on T-helper cells and is essential for their interaction with MHC class II molecules, while MHC class II molecules are important for antigen presentation to CD4+ T cells. Immunoglobulin receptors are mainly found on B cells, allowing them to bind to specific antigens. Thus, the presence of C3b complement receptors is distinctly characteristic of macrophages' role in innate immunity.