Final answer:
The mannan-binding lectin pathway of the complement system is activated by mannose-containing residues of glycoproteins on microbe surfaces, which leads to the pathogen's lysis. This pathway is part of the innate immune system and is independent of the antibody-mediated classical pathway.
Step-by-step explanation:
Activation of the Mannan-binding Lectin Pathway
The mannan-binding lectin pathway of complement is activated by mannose-containing residues of glycoproteins on the surfaces of microorganisms. Unlike the classical pathway, which is triggered by antibodies attached to the surface of a pathogen, the mannan-binding lectin pathway is part of the innate immune system and does not directly rely on the adaptive immune system for activation. Instead, it is triggered when mannan-binding lectin binds to specific carbohydrate patterns found on microbes, especially those that the body recognizes as foreign. This pathway then leads to a series of reactions that ultimately result in the lysis of the invading pathogen.
Therefore, the correct answer to this question is (a) mannose-containing residues of glycoproteins. It should be noted that the other options: (b) antigen-antibody complexes, (c) toll-like receptor binding, and (d) cytokines, are related to other aspects of immune responses but not the activation of the mannan-binding lectin pathway.