Question

During the study that engaged the influence of cytokinesis of making different immunoglobulin classes and also in development of hypersensitivity response type 1, researchers injected allergen X to WT mices VS mices with knockout to gene to IL4 cytokine. 10 days after the first injection the researches injected allergen X the second time and 14 days after the second injection the researchers measured the serum levels and the type of antibodies to allergen X. What will be the result? Explain! Thanks a lot!

Answer 1

In hypersensitivity type 1 , B-cells are stimulated (by CD4+TH2 cells) to produce IgE antibodies specific to an antigen. So TH2 is essential to be sensitized in order to activate B cell. Interleukin 4 have very important role with respect to T cell maturation. IL4 induces differentiation in TH2 cells which converts naive TH cells into active TH cells which can be sensitized by attaching itself to antigen. Once TH2 is stimulated it further stimulate B cells, which produces igE antibodies. High amount of IgE leads to type 1 hypersensitivity reaction.

So in case IL 4 is unavailable, TH2 cells will not mature and there will be no hypersensitivity reaction type 1.

In above mentioned case WT mice will have adequate production of IL4 which will lead to activation of TH2 cells and hypersensitvity will persist. So in first dose of antigen TH2 cells will be activated and B cells would have sensitized. At doses on 10 day and 14 day there will be immune response and very high amount of antigen specific IgE will be produced. So WT mice will suffer hypersensitivity type 1 reaction.

In case of VS mice IL4 gene is knocked out, which means the mice is unable to produce interleukin 4. So when it will be sensitized with antigen in absence on IL4 , there will be no TH2 response and IgE production. It means there will be no type 1 Hypersensitivity .