γ-Interferon-induced monocyte major histocompatibility complex class II antigen expression in individuals with acquired immune deficiency syndrome

Twelve patients with the acquired immune deficiency syndrome (AIDS) and Kaposi's sarcoma were treated with recombinant human γ-interferon (rIFN-γ). A rapid, substantial increase in the fraction of HLA-DQ-positive monocytes was noted after treatment with rIFN-γ. The rIFN-γ-induced increase in monocyte HLA-DQ was seen throughout the course of treatment, with the percentage of HLA-DQ-positive monocytes dropping slightly following each week's treatment with rIFN-γ and then rapidly increasing following the next course of treatment. Although the percentage of HLA-DR-positive monocytes was unchanged (HLA-DR was expressed on > 80% of monocytes prior to treatment), the density of HLA-DR on monocytes also increased following rIFN-γ treatment. Following rIFN-γ treatment, no changes were seen in CD3, CD4, CD8 T cell numbers, in T cell subset ratio (CD4/CD8), in Leu 7 or CD 16 (Leu 11) cell number, in spontaneous Ig secretion, in PHA-induced in vitro proliferation, or in NK activity. These results indicate that exposure to rIFN-γ in vivo led to the increased expression of class II antigens on monocytes in patients with AIDS.