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: Pathology
Which of the following feature is common to both cytotoxic T-cells and NK cells? 
Select and explain. 
A. Synthesis of antibody, B. Effective against virus infected cells, C. Requirement of antibodies for action, D. Recognize antigen in association with HLA class II markers
B: Effective against virus infected cells
Answer: B: Effective against virus infected cells 
Explanation: Cytotoxic T lymphocytes plays a protective role against virus associated neoplasms (EBV and HPV induced tumors) and have been demonstrated in the blood and tumor infiltrates of cancer patients.NK cells have the innate ability to lyse a variety of tumor cells, virally infected cells and some normal cells without prior sensitization. It is considered to be the first line of defence against neoplasm or viral infections. Ref: Robbins Pathologic Basis of Disease, 6th Edition, Page 191 and 8th Edition, Page 318