HIV p24 antigen concentration in serum of 11 anti-HIV 1-positive patients before and after immune-complex dissociation: a study of a 5-year period

Abstract Background: Determination of the p24 antigen of the human immunodeficiency virus type 1 (HIV 1) is widely used to monitor viral activity though it is well known that substructures with p24 specificity present in serum can be complexed with specific antibodies, thereby preventing them from being detected by regular p24 antigen detection assays. Objectives: To compare the regular assay for p24 antigen with a procedure that dissociates immune-complexes before determination of this antigen. Study design: Eleven HIV 1-infected patients were followed for up to 5 years in order to obtain continuity in terms of the development of the p24 antigen in comparison with other surrogate markers. Results: The results show that even low concentrations of anti-p24 antibodies are able to complex p24 antigens, rendering them undetectable in the routine assay. p24 antigens became detectable only after dissociation of these immune complexes by acid treatment procedure. In most patients viral activity became demonstrable only after application of the dissociation procedure.