Which of the following activates the classical complement pathway?
Ans: A (Immune complex) Ref: Ananthnarayan R, Partiker CKJ. Textbook of Microbiology. 8th Edition. Hyderabad: Universities Press: 2009.Explanation:Complement-pathwaysClassic pathway - Acquired immunity (Activated by antigen antibody complex)Alternate complement pathway - Innate immunity (Activated by various substances like bacterial endotoxins, fungal cell wall components like zymosan)Mannan/Mannose Binding Lectin pathway (MBL Pathway) - Innate immunity (Activated by the binding of mannose-binding lectin (MBL) to mannose residues on glycoproteins or carbohydrates on the surface of microorganisms including certain Salmonella, Listeria, and Neisseria strains, as well as Cryptococcus neoformans and Candida albicans.)Sources of ComplementClassical pathwayC1-epithelium & fibroblastsC3, C4. C6 -C9 -LiverCl -C5 -Macrophages (stimulated by phagocytic events)CI esterase -LiverAlternate pathwayFactor B. D. H. I. P -Macrophages (stimulated by phagocytic events)
Immune complex
Lipopolysaccharide
Exotoxin
Zymosan
Immunology