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
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 marker Lymphocytes and other leukocytes have a number of surface antigens or marker - leukocyte differentiation antigen. A paicular leucocyte differentiation antigen has been given a CD (cluster of differentiation) number on the bases of its reaction with a cluster of monoclonal antibodies. These markers reflect the stage of differentiation and functional propeies of cell.