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: Pathology
Which is a large granular lymphocyte? 
Select and explain. 
A. NK cell, B. B-lymphocyte, C. T-lymphocyte, D. Macrophage
A: NK cell
Answer: A: NK cell 
Explanation: Ans. (a) NK cell(Ref: Wintrobe's clinical hematology - 12th ed, pg 300; Robbins 9th/pg 192; 8th/pg 188)Most lymphocytes in blood are small (<=10mm), while some are large, known as large granular lymphocytes (LGL), as they contain azurophilic granules in their cytoplasm.These cells are LGL type of natural killer (NK) cells.