IMMUNOLOGY

Detailed explanation-1: -Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.

Detailed explanation-2: -Helper T cells secrete cytokines that help B cells differentiate into plasma cells. These cells also help to activate cytotoxic T cells and macrophages.

Detailed explanation-3: -The surface of a cytotoxic T-cell has something called a CD8 receptor. The CD8 receptor interacts with cells called major histocompatibility complex (MHC) Class I molecules to recognize when healthy cells are infected. When the CD8 receptor recognizes an infected cell, it activates the cytotoxic T-cells.

Detailed explanation-4: -Naïve CD4+ cells bind APCs via their antigen-embedded MHC II molecules and are stimulated to become helper T (TH) lymphocytes, cells that go on to stimulate B cells (or cytotoxic T cells) directly or secrete cytokines to inform more and various target cells about the pathogenic threat.

Detailed explanation-5: -In the case of B cells, once a helper T cell has been activated by an antigen, it becomes capable of activating a B cell that has already encountered the same antigen. Cytokines secreted by helper T cells can also interact with B cells and provide additional stimulation.