This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Cytokines are released by: September 2012 
Select and explain. 
A. Monocyte, B. Macrophage, C. T lymphocyte, D. B lymphocyte
C: T lymphocyte
Answer: C: T lymphocyte 
Explanation: 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.