ABSTRACT
Macrophages play a central role in modulating humoral and cellular immunity against infectious diseases and cancer. Immunomodulatory agents such as
interferon-
γ
(IFN
γ
) and
lipopolysaccharide
(LPS) are capable of activating them. Activated macrophages produce mediators of cytotoxicity such as
nitric oxide
(NO) and
tumor necrosis factor-
α
(TNF
α
), which protect the host against the development of infections and tumors. On the other hand, T lymphocytes respond to antigen challenge by proliferating and expanding the antigen-specific lymphocyte clones thus amplifying immune responses. Functional T cell proliferating activity can be studied by the use of polyclonal
mitogens such as
concanavalin A
(Con A) and
phytohemagglutinin
(PHA), which bind to certain sugar residues on T cell surface glycoproteins, including the T cell receptor and CD
protein, and stimulate T cell proliferative response.
