Question

Phagocytosis is the ingestion and destruction by individual cells of invading foreign particles such as bacteria. The phagocytic process is mediated mainly through two types of cell-surface receptors. The first is the Fc receptor that binds to IgG antibodies. What is the second is a receptor found on macrophages, monocytes, and PMNs?

a) CR3
b) CD1
c) CD45
d) CPP-32
e) CXCR4

Answer 1

The second cell-surface receptor involved in phagocytosis, besides the Fc receptor that binds to IgG antibodies, is CR3 (Complement Receptor Type 3).

Step-by-step explanation:

The second type of cell-surface receptor involved in phagocytosis is CR3 (Complement Receptor Type 3). This receptor is found on innate immune cells such as macrophages, monocytes, and polymorphonuclear neutrophils (PMNs). It plays a key role in the immune system by mediating the binding and ingestion of pathogens that are opsonized (marked) with complement proteins, which is a critical step in the phagocytic process to destroy invading foreign particles like bacteria.

Phagocytosis is the process by which large particles, such as cells, are taken in by a cell. For example, when microorganisms invade the human body, a type of white blood cell called a neutrophil removes the invader through this process. The first type of cell-surface receptor involved in phagocytosis is the Fc receptor that binds to IgG antibodies. The second receptor found on macrophages, monocytes, and PMNs is CR3.