Final answer:
T cells have a specialized antigen receptor that recognizes antigens presented by antigen-presenting cells within the context of MHC molecules, contributing to the adaptive immune system's response. There are different MHC classes for various types of T cells, and this interaction is critical for the activation and function of T cells.
Step-by-step explanation:
T cells recognize antigens with their antigen receptor, which is a complex of two protein chains found on their surface. These protein chains are most commonly referred to as alpha and beta T cell receptors. T cells can distinguish between self and non-self antigens through a process where antigens are presented by antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells in the context of a major histocompatibility complex (MHC) molecule.
There are two main types of MHC molecules: MHC class I, which is found on almost all cells and binds with CD8 molecules on cytotoxic T cells, and MHC class II, which is found on macrophages, dendritic cells, and B cells and binds with CD4 molecules on helper T cells.
The activation of T cells is crucial for the adaptive immune system to work effectively, and it occurs once the dendritic cell presents the processed antigens via MHC molecules. After activation, T cells, such as cytotoxic T cells, can then target and kill cells infected with pathogens, while helper T cells assist in the immune response regulation.