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
Activation of naive B lymphocytes by protein antigens is? 
Select and explain. 
A. T Cell independent, B. NK cell dependent, C. NK cell independent, D. T cell dependent
D: T cell dependent
Answer: D: T cell dependent 
Explanation: Ans. is d i.e., T cell dependent Upon activation, B lymphocytes proliferate and then differentiate into plasma cells that secrete different classes of antibodies with distinct functions. Antibody responses to most protein antigens require T cell help and are said to be T-dependent. Many polysaccharide and lipid antigens cannot be recognized by T cells but have multiple identical antigenic determinants (epitopes) that are able to engage many antigen receptor molecules on each B cell and initiate the process of B-cell activation; these responses are said to be T-independent.