<prompt> CD4 is marker ofMonocyteTcellBcellNone  <response>: Ref Robbins 7e p670;9e p191 There are 4 main types of T cells. CD4 Helper Cells. CD4 helper cells help in the maturation of B cells into plasma cells and memory B cells. ... CD8 Cytotoxic Cells. CD8 cytotoxic cells cause lysis of virus-infected and tumour cells. ... Memory T Cells. ... Natural Killer T Cells. 