What are the type and roles of T lymphocytes?

T lymphocytes recognize only peptide antigens bond to major histocompatibility complex (MHC) molecules expressed on the surface of antigen-presenting cells - CD4+ helper T lymphocytes: secretion of cytokines activating macrophages and differentiation and proliferation of lymphocytes and involved in inflammation. - CD8+ Cytotoxic T lymphocytes:recognize antigens and kill infected cells - CD4+ Regulatory T lymphocytes: limit activation of other T cells and suppress immune response to prevent autoimmunity.