This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Polysaccharide antigens are: 
Select and explain. 
A. T cell independent antigens, B. T cell dependent antigens, C. MHC I dependent antigens, D. MHC II dependent antigens
A: T cell independent antigens
Answer: A: T cell independent antigens 
Explanation: Ans. (a)For proteins and erythrocytes - T cell dependent antigens.For polysaccharides - T cell independent antigens.Protein antigens eliminated in days to weeks whereas polysaccharide antigens persist for months to years e.g., pneumococcal polysaccharide may persist upto 20 years in humans following a single injection.