il-7 and the TCR with the 3 different types of Follicular helper T cells.

There are 3 infection areas and there are 3 types of follicular helper T cells.

Th2 becomes TFH for the outer antigens.
TH1 becomes a TFH1 for the cytosol antigens.
Tc becomes a TFc for the mitochondrial and nuclear antigens.

il-7 is key to survival and size of T cell
https://www.ncbi.nlm.nih.gov/pubmed/11739504

il-7 involves the TCR rearrangement
https://www.ncbi.nlm.nih.gov/pubmed/9307061
http://www.pnas.org/content/107/43/18505

Hypothesis: il-7 replaces the need for strong TCR engagement.

il-7 is high in the B zone thus TCR engagement is not as critical. In the B zone the BCR is critical and the B cells BCR undergo somatic hypermutation.

In the B zone TH2 is converted to TFH with il-7receptors.

 Stimulated B cells make IgG1 with insulin, IgA with growth hormone, IgE with IGF-1.

In the T zone the TCR must be activated

CD4 TH1 like Tfh cells
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4607674/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3244883/
https://www.nature.com/articles/nri3161
http://www.jimmunol.org/content/197/5/1832

CD8 like Tfh cells
http://www.jimmunol.org/content/196/1_Supplement/186.1
https://www.nature.com/articles/srep30362

B cells with cd4 th1 make IgG2

B cells with cd8 TC make IgG3