Major differences in the responses of primary human leukocyte subsets to IFN-beta.
Treatment of cell lines with type I IFNs activates the formation of IFN-stimulated gene factor 3 (STAT1/STAT2/IFN regulatory factor-9), which induces the expression of many genes. To study this response in primary cells, we treated fresh human blood with IFN-β and used flow cytometry to analyze phosphorylated STAT1, STAT3, and STAT5 in CD4(+) and CD8(+) T cells, B cells, and monocytes. The activation of STAT1 was remarkably different among these leukocyte subsets. In contrast to monocytes and CD4(+) and CD8(+) T cells, few B cells activated STAT1 in response to IFN-β, a finding that could not be explained by decreased levels of IFNAR2 or STAT1 or enhanced levels of suppressor of cytokine signaling 1 or relevant protein tyrosine phosphatases in B cells. Microarray and real-time PCR analyses revealed the induction of STAT1-dependent proapoptotic mRNAs in monocytes but not in B cells. These data show that IFN-stimulated gene factor 3 or STAT1 homodimers are not the main activators of gene expression in primary B cells of healthy humans. Notably, in B cells and, especially in CD4(+) T cells, IFN-β activated STAT5 in addition to STAT3, with biological effects often opposite from those driven by activated STAT1. These data help to explain why IFN-β increases the survival of primary human B cells and CD4(+) T cells but enhances the apoptosis of monocytes, as well as to understand how leukocyte subsets are differentially affected by endogenous type I IFNs during viral or bacterial infections and by type I IFN treatment of patients with multiple sclerosis, hepatitis, or cancer.
Department of Molecular Genetics, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Anette H H
AH
van Boxel-Dezaire
Joana A
JA
Zula
Yaomin
Y
Xu
Richard M
RM
Ransohoff
James W
JW
Jacobberger
George R
GR
Stark
D017209:Apoptosis / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D002469:Cell Separation; D005434:Flow Cytometry; D015870:Gene Expression / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D050832:Interferon-Stimulated Gene Factor 3; D016899:Interferon-beta / Q000276:immunology* / Q000378:metabolism; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000276:immunology / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000276:immunology / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
D050832:Interferon-Stimulated Gene Factor 3; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D016899:Interferon-beta