what do cd4 cells do

CD4+ T cells, also known as helper T cells, are a type of white blood cell that helps coordinate the immune response against infection and disease. They interact and activate other cells in the immune system, such as macrophages, B lymphocytes, and CD8+ T lymphocytes, to fight infection. CD4+ T cells are activated after interaction with antigen-MHC complexes and differentiate into distinct effector subtypes that play a major role in mediating immune response through the secretion of specific cytokines. The CD4+ T cells carry out multiple functions, ranging from activation of the cells of the innate immune system, B-lymphocytes, cytotoxic T cells, as well as nonimmune cells, and also play a critical role in the suppression of immune reaction. Some CD4+ T cells can become activated and form memory T cells, which are important for the body to maintain long-term immunity against infection. CD4+ T cells can trigger and coordinate the immune response by recognizing pathogens and secreting cytokines that activate other immune cells, including CD8+ T cells. However, they have no direct involvement in attacking and neutralizing pathogens. In contrast, CD8+ T cells directly attack pathogens and cancerous cells by binding to them and secreting toxic molecules that stop pathogens from replicating and cause cell death.