Overview
Lymphocytes are the cells of adaptive immunity. B cells carry membrane immunoglobulin as their antigen receptor and make antibodies; T cells carry the T cell receptor and recognise peptide presented on MHC molecules. Other cells of the immune system include phagocytes, dendritic cells, NK cells and granulocytes, which act in innate immunity and help to start the adaptive response.
- T lymphocytes are a type of white blood cell essential for the adaptive immune response.
- They do not attack pathogens directly. Instead, they act on other cells in the body, particularly those that present antigens.
- T cells only recognize antigens when these are displayed in combination with the body’s own MHC (Major Histocompatibility Complex) molecules.
- There are three main subtypes of T cells:
- Cytotoxic T cells (Tc): Also called T killer cells
- Helper T cells (Th): Guide and coordinate immune responses
- Regulatory T cells (Treg): Modulate and suppress the immune response (not covered in detail here)