Besides an antigen receptor, what else do T cells have on their membrane?

• A. Immunoglobulins
• B. CD4 and CD-8 receptors
• C. Cytokine receptors
• D. Complement receptors

Answer: (B)

T cells are equipped with specific surface proteins that differentiate their functions and types. Among these, CD4 and CD8 receptors are critical components. CD4 receptors are found on helper T cells, which assist other immune cells by providing signals and enhancing the immune response. On the other hand, CD8 receptors are present on cytotoxic T cells, which are primarily involved in directly killing infected or cancerous cells.

The presence of these receptors is crucial for the proper functioning of T cells. They not only serve as co-receptors that recognize the major histocompatibility complex (MHC) molecules on other cells but also play a role in signaling pathways that activate T cells once they bind to their specific antigens presented by these MHC molecules. This dual recognition process ensures that T cells effectively identify and respond to pathogens or abnormal cells.

In contrast, while immunoglobulins are antibodies produced primarily by B cells, cytokine receptors are involved in the signaling pathways for various immune responses, and complement receptors are related to the complement system that aids in opsonization and cell lysis. These do not serve the same critical differentiation and activation roles that CD4 and CD8 receptors do for T cell function and specificity.