Macrophages are large phagocytic cells that can be found in tissues or as mobile white blood cells, particularly during infections. They exhibit surface CD3 expression and have several distinguishing features, such as abundant rough endoplasmic reticulum and receptors for C3b complement. Additionally, they are capable of synthesizing immunoglobulins in vitro.

1. Macrophages are characterized by:
A. surface CD3 expression
B. large amounts of rough endoplasmic reticulum
C. surface receptors for C3b complement
D. in vitro synthesis of immunoglobulin
Solution
1. Macrophages are a large phagocytic cell found in stationary form in the tissues or as a mobile
white blood cell, especially at sites of infection. They are characterized by surface CD3
expression.