Ultrasensitive quantification links higher serum interferon-α and interferon-γ levels with lower leukocyte and lymphocyte counts in lupus.

OBJECTIVES: Hematological abnormalities are common in systemic lupus erythematosus (SLE). Interferon-α (IFN-α) and interferon-γ (IFN-γ) play pivotal roles in the immunopathogenesis of SLE. However, their measurement in serum has long been limited by their extremely low circulating concentrations. With the advent of ultrasensitive detection technologies, these cytokines can now be reliably quantified. In this study, we investigated the association between serum levels of IFN-α and IFN-γ, measured using a highly sensitive assay, and the hematological abnormalities frequently observed in SLE. METHODS: In this cross-sectional study we recruited 313 patients with SLE. Complete blood counts, including red blood cells, white blood cells, and platelets, were obtained, and serum IFN-α and IFN-γ levels were quantified using the ultrasensitive Single Molecule Array (Simoa) platform. Multivariable linear and logistic regression analyses were performed to evaluate the associations between IFN concentrations and hematological parameters. RESULTS: In multivariable analyses, higher serum levels of both IFN-α and IFN-γ were significantly associated with lower total leukocyte, neutrophil, and lymphocyte counts. Platelet and red cells count were not significantly associated with both IFNs. Logistic regression analyses further confirmed that elevated serum concentrations of IFN-α and IFN-γ were independently associated with increased odds of leukopenia and lymphopenia, analyzed as binary outcomes, after adjustment for relevant covariates. CONCLUSION: Elevated serum IFN-α and IFN-γ levels are independently associated with reduced leukocyte and lymphocyte counts in patients with SLE.