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
Thomsen friedensreich phenomenon is ? 
Select and explain. 
A. Red cells infection by CMV, B. Red cell agglutination by all blood group sera, C. Hemolysis of transfused blood, D. Due to B antigen
B: Red cell agglutination by all blood group sera
Answer: B: Red cell agglutination by all blood group sera 
Explanation: Ans. is 'b' i.e., Red cell agglutination by all blood group sera Thomsen-Freidenreich Phenomenon Red cell suspensions contaminated with ceain bacteria, e.g. pseudomonas aeruginosa, become agglutinable by all blood group sera and even by normal human sera. This is known as Thomsen Friedenreich phenomenon and is due to unmasking of a hidden antigen normally present on all human erythryocytes, i.e. T-antigen. Anti-T agglutinins are normally present in human sera. Such panagglutinability of red cells has occasionally been observed in persons suffering from systemic bacterial infections.