The ratio of the number of helper T lymphocytes to the number of suppressor and cytotoxic T lymphocytes. The cells are counted with the use of monoclonal antibodies to the surface glycoproteins CD4 on helper T cells and CD8 on suppressor and cytotoxic T cells. In healthy individuals the ratio ranges from 1.6 to 2.2. The ratio is important in monitoring the function of the immune system in patients who have viral infections or who have undergone tissue transplantation, either of which may cause an increase in the number of suppressor T cells.