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
Macrophages- false statement is? 
Select and explain. 
A. Derived from monocytes, B. Harbor Mycobacteria, C. Involved in Type 3 HSN, D. Produces TNF and interleukins
C: Involved in Type 3 HSN
Answer: C: Involved in Type 3 HSN 
Explanation: Ans. (c) Involved in Type 3 HSN(Ref: Robbins 9th/pg 210)A. TrueMonocytes in tissues are known as MacrophagesB. TrueMacrophages engulf Mycobacteria but are not able to kill it; So they harbor MycobacteriaC. FalseMacrophages are involved in Type 4 Hypersensitivity & not type 3, which is immune- complex mediatedD. True*. Macrophages secrete TNF, IL-1, and chemokines, which promote inflammation*. Macrophages also produce IL-12, thereby amplifying the TH1 response