I found this interesting:
The CD4/CD8 T-cell ratio in humans is genetically controlled [
62], with at least some of the responsible genes being located in the HLA complex [
63].
The CD8+ T cell deficiency and increased CD4/CD8 ratio in autoimmune diseases are also present in healthy blood relatives of patients with these diseases, indicating that the abnormalities are genetically determined and not secondary for the disease process. Interestingly, females generally have lower proportions and numbers of CD8+ T cells, higher proportions and numbers of CD4+ T cells, and higher CD4/CD8 ratios than males [
62,
66–
70]. These gender differences appear to be hormonally mediated because oestrogen deficiency substantially increases the proportion and number of CD8+ T cells and decreases the CD4/CD8 ratio, with the ratio directly correlating with the serum oestradiol level [
71]. Lower numbers of CD8+ T cells in females might contribute to the higher frequency of autoimmune diseases in females than males. Because the number of CD8+ T cells normally declines with increasing age, particularly through childhood [
72], but also through adulthood [
62,
70,
73], the primary CD8+ T cell deficiency will be aggravated as each person ages, as occurs in patients with MS [
74] (Figure
3).
https://www.hindawi.com/journals/ad/2012/189096/