<prompt> CD 4 are associated with -Helper T cellSupressor T cellNK cellsT cell antigen receptor complex  <response>: T cells can differentiate into effector cells. Helper CD4 T-cell activity, in addition to stimulating B cells to produce antibodies, promotes the development of delayed hypersensitivity and thereby also serves in the defense against intracellular agents, including intracellular bacteria eg, mycobacteria, fungi, protozoa, and viruses. Reff: Ananthanarayanan Panikers textbook of microbiology 9th edition pg: 135 