<prompt> Which of the following best denotes classical complement pathway activation in immune inflammatory condition:C2, C4 and C3 decreasedC2 and C4 normal, C3 is decreasedC3 normal and C2, C4 decreasedC2, C4, C3 all are elevated  <response>: Classical complement pathway involves reduction in all complement components C1 to C9 Alternate pathway causes depletion of all components except C1, C2 and C4Complementsheat labile proteins found in serumproduced by the liver:Classical pathway Alternate pathwayActivated by antigen antibody reaction does not need antigen antibody reaction Antigen antibody binding activates activated by Complement C1 and initiates the cascade IgG complexes Complex carbohydrates Endotoxins Properidin Serum factors B D Magnesium ions activation occurs directly at C3 level And doesnot involve early factors C1, C4 C2ref: Harrisons 18e p1011 