T helper cell

Activation of macrophage or B cell by T helper cell The T helper cells (Th cells), also known as CD4 cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considered essential in B cell antibody class switching, breaking cross-tolerance in dendritic cells, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages and neutrophils. CD4 cells are mature Th cells that express the surface protein CD4. Genetic variation in regulatory elements expressed by CD4 cells determines susceptibility to a broad class of autoimmune diseases.

Structure and function