Human B cells fail to secrete type I interferons upon cytoplasmic DNA exposure

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Type I interferons (IFN I) are crucial for innate immunity against viral infections.
• Macrophages induce IFN I upon detecting foreign nucleic acids via sensors like IFI16 and cGAS, activating STING, TBK1, and IRF3.
• Human gamma-herpesviruses, like Epstein-Barr virus (EBV), persist in B cells.

Purpose of the Study:

• To investigate if human B cells activate the cytoplasmic DNA sensing pathway for innate immune response.
• To determine the mechanisms behind potential IFN I induction defects in B cells.

Main Methods:

• Analysis of IFN I secretion in primary human B lymphocytes and B cell lines upon stimulation with cytoplasmic DNA or cGAMP.
• Assessment of DNA sensors (IFI16, cGAS) and signaling components (STING, TBK1, IRF3) expression.
• Functional assays involving STING-reconstituted cells.

Main Results:

• Human B cells, unlike macrophages, fail to secrete IFN I upon cytoplasmic DNA exposure.
• Primary B cells and EBV-negative B cell lines lack detectable STING protein, a key adaptor in the pathway.
• EBV-transformed B cells express STING, but still do not produce IFN I upon stimulation, indicating further pathway defects.

Conclusions:

• The cytoplasmic DNA sensing pathway is dysfunctional in human B cells.
• This cellular defect, particularly the STING deficiency, may create a niche for viral persistence, such as EBV.
• Certain cell types possess inherent limitations in their innate immune response to cytoplasmic DNA.