CD8⁺ T cell-mediated suppression of human immunodeficiency virus replication in older children with acquired immunodeficiency syndrome

Background. Suppression of HIV replication by CD8⁺ T cells and/or their products correlated with the survival of infants. We sought to elucidate the role of CD8⁺ T cell-mediated suppression in seven older children with AIDS. Methods. After separation of each child's CD4⁺ and CD8⁺ T cells, three different HIV culture assays were performed: (1) patient CD4⁺ T cells and phytohemagglutinin (PHA)-stimulated donor peripheral blood mononuclear cells (PBMC); (2) patient CD8⁺ T cells added to the CD4⁺ T cells and the PHA- stimulated donor PBMC (to test for CD8-mediated T cell suppression of HIV) (3) patient CD8⁺ cells added across a semipermeable membrane to the CD4⁺ T cells and the PHA-stimulated donor PBMC [to determine whether the CD8 cells secreted a soluble factor(s) that suppressed HIV]. Results. Cultures from four of seven children showed greater HIV replication with CD4 cells alone than with CD4 and CD8 cells together, demonstrating CD8 suppression; evidence of soluble suppression was also seen. Cultures from two of the seven children showed HIV replication and no evidence of CD8 cell suppression. Cultures from one of the seven children had no appreciable replication of HIV even after removal of CD8 cells. Conclusions. CD8-mediated suppression is present in at least some children with AIDS. Additional mechanisms may be operating to slow the progression of the disease.