Although the expression of Ro52α and Ro52γ can explain the binding of anti-Ro52Ex4 antibodies to SLE neutrophils, the sole expression of these isoforms (molecular weights 52 and ~33 kDa, respectively) is insufficient to elucidate the origin of the broad range of bands containing the Ro52Ex4 epitope, which are detected in IFN-activated SLE neutrophils. This evidence concerns the gene IFNA1 and systemic lupus erythematosus.