IMMUNOGLOBULINS
CLASSICAL ALTERNATE AND LECTIN PATHWAYS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Adhesion and increased activity of phagocytic cell
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B cell coreceptor for antigen with Cd19
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Cofactor for factor I cleavage of C3b and C4b
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Dissociates C2b or Bb from binding sites
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Detailed explanation-1: -DAF is a 70, 000-Mr membrane protein that inhibits the amplification of the complement cascade on the cell surface, and protects cells from damage by complement. The precise mechanism of action of DAF is not entirely clear. Purified DAF was incorporated into the membrane of EAC4b cells.
Detailed explanation-2: -The C4b2a complex, or C3 convertase, catalyzes the cleavage of C3 into C3a and C3b. This is the most important step in the complement cascade and occurs in the classic, alternative, and MBL pathways. C3b is a highly unstable molecule that has a unique thioester that allows covalent binding to a microbial cell.
Detailed explanation-3: -C3 convertase (C4bC2b, formerly C4b2a) belongs to family of serine proteases and is necessary in innate immunity as a part of the complement system which eventuate in opsonisation of particles, release of inflammatory peptides, C5 convertase formation and cell lysis.