Final answer:
CD4+ T helper cells specifically bind to MHC class II molecules on antigen-presenting cells. This binding is essential for the activation of T helper cells and subsequent cytokine release, which plays a significant role in the immune response.
Step-by-step explanation:
CD4+ T helper cells are key players in the immune system. They are responsible for binding to MHC class II molecules that are found on the surface of antigen-presenting cells such as macrophages, dendritic cells, and B cells. This interaction is crucial for the activation of CD4+ T helper cells.
When a CD4+ helper T cell binds an MHC II-antigen complex on an antigen-presenting cell, both cells are involved in the release of cytokines, which are signaling proteins that contribute to the immune response. Specifically, the T cell receptor (TCR) on a helper T cell binds to antigens that are presented with MHC II molecules, not MHC class I. This distinct interaction is part of what characterizes CD4+ helper T cells and differentiates them from cytotoxic T cells, which typically bind to MHC class I. The CD4 molecule on the helper T cells acts as a coreceptor in this binding process.