Final answer:
CR3 and CR4 receptors on T cells recognize foreign epitopes presented with MHC I or MHC II. They play a crucial role in immune responses by recognizing bacterial and fungal pathogens, viral-infected cells, and tumor cells. Additionally, CR3 and CR4 help facilitate antigen presentation and enhance T cell activation.
Step-by-step explanation:
CR3 and CR4 are receptors found on T cells that recognize processed foreign epitopes presented with MHC I or MHC II. These receptors play a crucial role in the immune response by binding to antigens and initiating an immune reaction.
Some of the things that CR3 and CR4 recognize include bacterial and fungal pathogens, viral-infected cells, and tumor cells. By recognizing these foreign invaders, T cells can mount an immune response to eliminate them.
Additionally, CR3 and CR4 are important in the process of antigen presentation, where they help facilitate the binding of antigens to MHC molecules and enhance T cell activation. This recognition is essential for the immune system to differentiate between self and non-self molecules and mount an appropriate immune response.