Cell Surface Proteins

T cells	TCR (binds antigen-MHC complex) CD3 (associated with TCR for signal transduction) CD28 (binds B7 (CD80/86) on APC)
Helper T cells	CD4, CD40L, CXCR4/CCR5 (co-receptor for HIV)
Cytotoxic T cells	CD8
Regulatory T cells	CD4, CD25
B cells	Ig (binds antigen) CD19, CD20, CD21 (receptor for EBV), CD40 MHC II, B7 You can drink Beer at the Bar when you’re 21: B cells, Epstein-Barr virus, CD21.
Macrophages	CD14 (receptor for PAMPs, eg, LPS), CD40 CCR5 MHC II, B7 (CD80/86) Fc and C3b receptors (enhanced phagocytosis)
NK cells	CD16, CD56 (suggestive marker for NK)
Hematopoietic stem cells	CD34