Peripheral T lymphocyte depletion by apoptosis after CD4 ligation in vivo: Selective loss of CD44 super(-) and 'activating' memory T cells

We have demonstrated that a single intravenous bolus of rat anti-CD4 MoAb caused a small but prolonged increase in apoptosis in murine lymph nodes. We have quantified this process using the novel Highly Optimized Microscope Environment (HOME) interactive image analysis system and shown that the increase in apoptosis was sufficient to account for the observed depletion of the peripheral CD4 super(+) T cell subset. This occurred in the absence of any other exogenous signal. Furthermore, there was no evidence of an inflammatory or necrotic response in the tissues, indicating that this was unlikely to be Fc or complement-mediated antibody killing. The anti-CD4-induced depletion selectively removed CD44 super(-) T cells. These results have implications for the pathology of HIV-associated disease which is associated with ligation of CD4 molecules in vivo.