<prompt> Cytokines are released by: September 2012MonocyteMacrophageT lymphocyteB lymphocyte  <response>: Ans. C i.e. T lymphocyte T helper cells Th cells They are a sub-group of lymphocytes that play an impoant role in the immune system, paicularly in the adaptive immune system. They help the activity of other immune cells by releasing T cell cytokines. They are essential in B cell antibody class switching, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages. 