Normal CD4:CD8 ratio is

Ans. b (2:1) (Ref. Harrison's Principles of Internal Medicine 16th ed., 2019)CD4/CD8 Ratio# The ratio of 2:1 found in normal tissues.# In HIV infection the CD4 count is often decreased and the CD8 count increased so the ratio might 'invert', that is become less than 1.AIDS Diagnosis:* < 200 CD4 count,* HIV Positive with Aids indicator conditions (E.g., PCP),or* CD4/CD8 ratio < 1.5.# Lymphopenia predominantly due to selective loss of the CD4+ helper-inducer T-cell subset; inversion of CD4:CD8 ratio.CD4 Cell# Also known as "T4" or "helper T cell," the CD4 cell is the primary target of HIV.# It performs critical functions such as signaling other parts of the immune system to respond to an infection.# There are two main types of T-cells.- T4 cells, also called CD4+, are "helper" cells.* They lead the attack against infections.- T8 cells (CD8+) are "suppressor" cells that end the immune response.* CD8+ cells can also be "killer" cells that kill cancer cells and cells infected with a virus.# Treatment decisions are often based on viral load and CD4 count.# Normal counts range from 500 to 1500.