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What is Normal ratio of CD4 (T4) : CD8 (T8) is and explain in detail?
Both CD4+ and CD8+ T cells contain several subsets. The CD4+/CD8+ ratio in the peripheral blood of healthy adults and mice is about 2:1, and an altered ratio can indicate diseases relating to immunodeficiency or autoimmunity. An inverted CD4+/CD8+ ratio indicates an impaired immune system. 
Ref :https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5667733