By Levi Clancy for Student Reader on
- Antibody techniques
You get normal development except there are no plasma cells. IL-6 is required for plasma cell development.
AID is an enzyme needed for somatic hypermutation (affinity maturation, and more) and also isotype switching (cytokines are needed simultaneously for isotype switching). You get normal development of B and T cells. However all of the B cells remain IgM positive; there is no isotype switching.
Ig-α or -β
T cell development, which does not require Igα is normal. However, B cell development is arrested in the bone marrow and mature B cells are not present in the secondary lymphoid organs. Igα is required for surface expression of the BCR.
Needed for antigen specificity -- but after that, not needed. Thus, they are not needed for isotype switching. Lack of RAG enzymes leads to no antibody production and no T cell maturation (arrested at DN stage). There is impaired development of both B and T cells. RAG is required for somatic assembly of both the B and T cell receptors. Without correctly assembled receptors, T and B cells do not develop.
Class I MHC
CD4 cells would not be present, so no memory B cell responses, CD4 responses or CD8 responses. A + for CD8 response is OK, as some CD8 responses do not need help. There would be low levels of IgM in initial and secondary infections.
Class II MHC
As a result there would be no MHC II on the thymic epithelial cells, no positive selection for CD4 SP cells and consequently no CD4 SP cells. This would then cause immunodeficiency due to lack of any CD4 help to B-cells to give CD40 stimulation and promote class switching. Likewise, there would be no help for the CTL response.