Phagocytes have a role in recognition and elimination of microbes by reactive oxygen species or antigens by opsonisation

T cells

Cytotoxic (CD8) T cells recognise MHC class I molecule antigens

T helper (CD4) cells recognise MHC class II molecule antigens.

MHC class I proteins are present on all nucleated cells. MHC class I molecules

(rather than class II) allow self recognition.

MHC class II proteins are only expressed on dendritic cells, macrophages, B-cells as antigen presenting cells .