Table 3. Cells, factors, and functions in adaptive immunity.

Cells and systems	Important functions
APCs	Detect, engulf antigens, present fragments
Dendritic cells	Prime lymphocytes, secrete cytokines
Macrophages	Phagocytose, present, secrete cytokines
B cells	Engulf antigens, process, present fragments, differentiate, produce antibody
T cells
CD8+ cytotoxic killer	Recognize, kill, secrete cytokines
Natural killer T cells	Recognize lipid antigens
CD4+ Helper*
T helper 1	Secrete cytokines, aid humoral responses
T helper 2	Secrete cytokines, aid cytotoxic T cells
Suppressor T cells	Suppress T or B cell responses

T helper 1 and 2 cytokines are mutually antagonistic.