Question

When complement proteins are covalently deposited onto the surface of a bacterium, this can sometimes lead to direct lysis of the bacterium. However, more commonly, the deposition of complement proteins onto the bacterial surface does not directly harm the bacterium. Instead, these complement proteins aid in bacterial elimination by? Please explain?

a. Providing a mechanism for phagocytes to use their Fc receptors to recognize and ingest the bacterium

b. Providing a mechanism for phagocytes bearing complement receptors to recognize and ingest the bacterium

c. Recruiting antibodies to the bacterial surface, leading the antibody-dependent neutralization

d. Cross-linking carbohydrate structures on the bacterial surface, thereby preventing the bacterium from replicating

e. Stimulating B lymphocytes to produce more antibodies against the bacterium

Can your immune system kill helminths and protozoan parasites why?

Answer 1

B is the right answer. The complement protein aids in bacterial elimination by providing mechanism for phagocytes bearing complement receptors to recognize and ingest the bacterium. The complement system opsonizes the antigen or marks and identifies the antigen and this enhances the immune response and now the complement system would attract the macrophages for phagocytosis towards the marked or opsonized antigen (bacteria) and now the cell digestion starts by the action of hydrolytic enzymes.