Question

48) Which of the following proteins of the complement cascade is an opsonin?

A) factor P

B) MAC

C) C3a

D) C5a

E) factor B

73) The molecular interaction between an antigen presenting cell and a T cell is

A) a dendrite.

B) an immunological synapse.

C) regulatory TCR.

D) CD95L.

E) clonal expansion.

87) Monoclonal antibodies are obtained from

A) human B cells in culture.

B) human serum.

C) animal serum.

D) hybridomas.

E) both human and animal serum.

Answer 1

48) Answer is C3b

The complement protein C3a acts as anaphylactic factor whereas C3b acts as opsonin. C3b binds to the outer surface of any foreign cell and make them more immunogenic. Phagocytic cells have receptors for C3b, so that foreign cell surface bound C3b bring the foreign cell towards phagocytic cells and binds to the receptor and help phagocytic cells to engulf the foreign cell.

73) Answer is option B

Immunological synapse is formed when antigen presenting cells present degraded foreign peptides via MHC class II to the haplotype specific TCR ( T-cell receptor) of the T cell, so that activation of T-cell occurs.

87) Answer is option D.

Monoclonal antibodies are produced by hybridoma technology. Here B cells and Myeloma cells are fused in presence of PEG( poly ethylene glycol) and selected in HAT medium. The hybrid cells are selected out and help in production of monoclonal antibodies.