Question

Do T cells comprise 90% of the circulating lymphocytes?

Answer 1

No, they don't.

Explanation:

Lymphocytes migrate in and out of the blood, and spend most of their time in the body’s connective tissues and lymphatic organs.

Lymphocytes are part of the body’s specific defense system. (a one-to one system).

There are 3 functional classes of lymphocytes:
1. T cells (cell-mediated immunity) attack foreign cells directly
2. B cells (humoral immunity) differentiate into plasma cells which synthesize antibodies
3. Natural killer (NK) cells detect and destroy abnormal tissue cells such as cancers

Depending on the laboratory, most people who are not immune compromised, have T-cells that range from 25-45% of their total lymphocyte count.