Blind T-cell homeostasis and the CD4/CD8 ratio in the thymus and peripheral blood

We present a model of the dynamics of CD4 and CD8 T-cell subsets in the thymus and peripheral blood and use it to study the blind homeostasis hypothesis, which states that the total T-cell population in the periphery is subject to regulation rather than regulation of the CD4 or CD8 subsets individually. Our model reconstructs experimental observations by Adleman and Wofsy on the effects of CD4⁺ T-cell depletion in mice. Our results point to the importance of the thymus in recovery from CD4⁺ T-cell depletion and particularly to the need to hypothesize an intrathymic feedback regulation of T-cell production exerted by CD4⁺ T cells. Our results support the blind homeostasis hypothesis for regulation of the peripheral blood levels of CD4⁺ and CD8⁺ T cells.