immuno question - poojy36

[ArchivalUser]

a 5 yr old boy with recurrent ear infections receives immunisation with DPT vaccine.his humoral response to tetanus(tt) is below normal .peripheral bcell and T cell count and function is normal.The antibody he makes is positive in passive agglutination and complment mediated lysis of tt coated erythrocytes.His antibody does not opsonise ttcoated latex particles for phagocytocis and do not precipitate tt effectively.The child has a defect in which process//

a)affinity maturation of antibody
b)immunoglobulin isotype switching
c)recobination of heavy chain variable regions
d)recombination of light chain variable region
e)somatic mutation of immunoglobulin gene

[ArchivalUser]

He can make only IgM (The antibody he makes is positive in passive agglutination and complment mediated lysis of tt coated erythrocytes), but can't make IgG (His antibody does not opsonise ttcoated latex particles for phagocytocis and do not precipitate tt effectively), only IgG opsonize, right?

So the problem is class switching.

Answer B.

[ArchivalUser]

thanks