Quantification of alphafetoprotein (AFP) endocytosis by PHA-activated peripheral blood mononuclear cells (PBMC) from HIV-infected individuals. A useful test of predictive value for the progression of AIDS.

Serum alphafetoprotein (AFP) is actively taken up, through receptor-mediated endocytosis, by many embryo-fetal cells during ontogenic development but also by neoplastic cells, as well as by normal peripheral T lymphocytes after mitogenic activation. We have previously shown that the ability to internalize AFP is impaired in mitogen-activated T cells from several groups of (HIV+)-seropositive individuals and that this expression roughly correlates with the progression of the disease. It is not clear whether this impaired AFP-endocytosis results from an HIV-mediated inhibition of AFP-receptor expression or if it is the consequence of a target signal transduction impairment due to HIV-infection. In the present work we have explored both possibilities by studying AFP-endocytosis in peripheral blood mononuclear cells (PBMC) from seropositive (HIV+)-asymptomatic heterosexual individuals and in in vitro HIV-infected PBMC from healthy donors, either quiescent or stimulated with phytohemagglutin (PHA). Our results suggest that this novel abnormality of T-cells associated with HIV-infection reflects an unusual proliferative response of PBMC to mitogenic stimuli.