Monocyte response to SARS-CoV-2 protein ORF8 is associated with severe COVID-19 infection in patients with chronic lymphocytic leukemia.

The open reading frame 8 (ORF8) protein, encoded by the SARS-CoV-2 virus after infection, stimulates monocytes/macrophages to produce pro-inflammatory cytokines. We hypothesized that a positive ex vivo monocyte response to ORF8 protein pre-COVID-19 would be associated with subsequent severe COVID-19. We tested ORF8 ex vivo on peripheral blood mononuclear cells (PBMCs) from 26 anonymous healthy blood donors and measured intracellular cytokine/chemokine levels in monocytes by flow cytometry. The % monocytes staining positive in the sample and change in mean fluorescence intensity (ΔMFI) after ORF8 were used to calculate the adjusted MFI for each cytokine. We then tested pre-COVID-19 PBMC samples from 60 CLL patients who subsequently developed COVID-19 infection. Severe COVID-19 was defined as hospitalization due to COVID-19. In the 26 normal donor samples, the adjusted MFI for interleukin (IL)-1β, IL-6, IL-8, and CCL-2 were significantly different with ORF8 stimulation vs controls. We next analyzed monocytes from pre-COVID-19 PBMC samples from 60 CLL patients. The adjusted MFI to ORF8 stimulation of monocyte intracellular IL-1β was associated with severe COVID-19 and a reactive ORF8 monocyte response was defined as an IL- 1β adjusted MFI ≥ 0.18 (sensitivity 67%, specificity 75%). The median time to hospitalization after infection in CLL patients with a reactive ORF8 response was 12 days versus not reached for patients with a non-reactive ORF8 response with a hazard ratio of 7.7 (95% CI: 2.4-132, p=0.005). These results provide new insight on the monocyte inflammatory response to virus with implications in a broad range of disorders involving monocytes.