Which marker is associated with T helper cells?

The marker that is primarily associated with T helper cells is CD4. T helper cells play a crucial role in the immune response by assisting other immune cells, including B cells and cytotoxic T cells, by providing necessary signals and cytokines. The presence of the CD4 marker on the surface of these cells distinguishes them from other T cell subtypes.

CD4 acts as a co-receptor that enhances the interaction between T cell receptors and the major histocompatibility complex (MHC) class II molecules found on antigen-presenting cells. This interaction is essential for the proper activation and functioning of T helper cells. In contrast, other markers like CD3 are found on all T cells and are involved in T cell activation, CD8 is predominantly expressed on cytotoxic T cells, and CD19 is a marker primarily associated with B cells, indicating that their roles are distinct in the immune system.