Infections have been proposed as an environmental risk factor for autoimmune disease. Responses to microbial antigens may be studied in vivo during vaccination. We therefore followed patients with SLE and controls during split-virion influenza vaccination to quantify antibody responses against viral antigens and associated cellular and proteome parameters.

Blood samples and clinical data were collected from female patients with SLE with no or HCQ and/or low-dose prednisolone treatment (n = 29) and age- and sex-matched healthy controls (n = 17). Vaccine-specific antibody titres were measured by ELISA and IFN-induced gene expression in monocytes by quantitative PCR. Serum proteins were measured by proximity extension assay and disease-associated symptoms were followed by questionnaires.

The vaccine-specific antibody response was significantly higher in patients compared with controls and titres of IgG targeting the viral proteins were higher in patients than controls at both 1 and 3 months after immunization. Clinical disease symptoms and autoantibody titres remained unchanged throughout the study. Notably, a positive pre-vaccination mRNA-based IFN score was associated with a significantly higher vaccine-specific antibody response and with a broader profile of autoantibody specificities. Screening of serum protein biomarkers revealed higher levels of IFN-regulated proteins in patients compared with controls and that levels of such proteins correlated with the vaccine-specific IgG response, with C-C motif chemokine ligand 3 exhibiting the strongest association.

Augmented antibody responses to viral antigens develop in patients with SLE on no or light treatment and associate with markers of type I IFN system activation at the RNA and protein levels.