title: Interleukin 12-augmented T cell proliferation of peripheral blood mononuclear cells from HIV-seropositive individuals is associated with interleukin 12 receptor beta 2 upregulation.
abstract: Interleukin 12 (IL-12) production is believed to be impaired in individuals with HIV infection and this impairment manifests early in disease, when the CD4(+) cell counts are within normal values. The reduced antigen-specific and mitogen-stimulated T cell-proliferative responses that occur in HIV infection can be corrected by the addition of recombinant human interleukin 12 (rhIL-12). As the IL-12 receptor (IL-12R) is central to the IL-12 signaling pathway, we examined whether the augmentation of antigen-specific proliferation of HIV(+) peripheral blood mononuclear cells (PBMCs) related to altered IL-12R expression. rhIL-12 augmented antigen-specific proliferation of HIV(+) PBMCs but not of HIV(-) PBMCs. Examination of resting PBMCs from HIV(+) and HIV(-) donors showed that neither of these populations expressed IL-12R beta 1 or IL-12R beta 2 chains on their cell surface as detected by flow cytometry. However, examination of mRNA showed that both IL-12R beta 1 and IL-12R beta 2 mRNAs were markedly reduced in HIV(+) PBMCs when compared with HIV(-) PBMCs. After mitogen activation there was an increase in IL-12R beta 1 expression on the cell surface of HIV(+) and HIV(-) PBMCs and this level was not altered by coculture with rhIL-12 or interferon gamma (IFN-gamma). However, coculture of phytohemagglutinin (PHA)-activated HIV(+) or HIV(-) PBMCs with rhIL-12 (but not IFN-gamma) increased IL-12R beta 2 expression on the cell surface of both populations. Examination at the message level showed a correction of IL-12R beta 1 to normal levels with activation that was further enhanced by rhIL-12 coculture for both the HIV(+) and HIV(-) PBMCs. However, although the level of IL-12R beta 2 for the HIV(+) PBMCs was normalized by PHA, rhIL-12 caused a further augmentation. This information provides a strong link between IL-12R upregulation, and the significant improvement in antigen-specific HIV-proliferative responses seen with the addition of rhIL-12. It also reveals that the dysfunction in IL-12R expression seen in cells from HIV(+) patients occurs at the transcriptional level. In addition, we provide further evidence that IL-12R beta 1 and IL-12R beta 2 regulation in human PBMCs is independent of IFN-gamma.
authors.affiliation: Department of Immunopathology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Wentworthville, NSW 2145, Australia.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Jones
authors.forename: Judy M
authors.initials: JM
authors.lastname: Young
authors.forename: Qi Rong
authors.initials: QR
authors.lastname: Huang
authors.forename: Rebekah L
authors.initials: RL
authors.lastname: Puls
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Webber
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Benson
mesh_terms: D015658:HIV Infections / Q000276:immunology*; D018023:HIV Seronegativity / Q000276:immunology; D006679:HIV Seropositivity / Q000276:immunology; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D018664:Interleukin-12 / Q000235:genetics / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008213:Lymphocyte Activation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics / Q000378:metabolism*; D053707:Receptors, Interleukin-12; D011994:Recombinant Proteins / Q000276:immunology; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053707:Receptors, Interleukin-12; D011994:Recombinant Proteins; D018664:Interleukin-12