This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Microbiology
CD 3 receptor is seen in - 
Select and explain. 
A. T cells, B. B cells, C. Macrophages, D. Eosinophils
A: T cells
Answer: A: T cells 
Explanation: Ans. is 'a' i.e., T cells CD markero Lymphocytes and other leukocytes have a number of surface antigens or marker - leukocyte differentiation antigen.o A particular leucocyte differentiation antigen has been given a CD (cluster of differentiation) number on the bases of its reaction with a cluster of monoclonal antibodies,o These markers reflect the stage of differentiation and functional properties of cell.Leucocyte differentiation antigens (a few examples)CD numberCell type associationCD 1CD 2CD 3CD 4CD 8CD 19Thymocytes, Langerhans cellsT cell SRBC receptorT cell antigen receptor complexHelper T cell (receptor for HIV)Suppressor/cytotoxic T cellsB cells