Higher pro-inflammatory cytokines IL-6 and IFN-γ are associated with anti-SARS-CoV-2 spike protein-specific seroconversion in renal allograft recipients.

ABSTRACT

BACKGROUND: Maintenance immunosuppressive regimens are speculated to hamper immunogenic response against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) in renal transplant recipients (RTRs) compared to the healthy population. Healthy people with SARS-CoV-2 infection often develop neutralizing antibodies and secret copious quantities of cytokines, leading to virus clearance and sometimes more severe immune-related complications. METHODS: RTRs, either acquired SARS-CoV-2 infection (infection group, n = 132) or were vaccinated with two vaccine doses (vaccination group, n = 78) against SARS-CoV-2, were recruited in the study. Thirty-five unvaccinated RTRs, without anti-SARS-CoV-2 spike protein-specific antibodies, were also included as control. Cytokines interleukine-6 (IL-6), interferon-γ (IFN-γ), TGF-ß, and IL-10 were measured using ELISA. The SARS-CoV-2 spike protein-specific IgG-titer was measured by chemiluminescent microparticle immunoassay methods. RESULTS: The seroconversion rate in the infection group was 115/132 (87.12%), with a median antibody titer 706.40 au/mL (IQR, 215.45-1844.42), and in the vaccination group was 63/78 (80.76%) with antibody titer 1454.20 au/mL (IQR, 80.52-3838.75). The IL-6, IFN-γ, TGF-ß, and IL-10 levels were significantly higher in both the infection and vaccination group compared to healthy control. In the infection group, pro-inflammatory cytokines IL-6 (55.41 ± 24.30 vs. 31.64 ± 16.98 pg/mL, p < .001) and IFN-γ (91.21 ± 33.09 vs. 61.69 ± 33.28 pg/mL, p = .001) were significantly higher in the seroconverter group as compared to non-seroconverter. Similarly, in the vaccination group, pro-inflammatory cytokines IL-6 (50.31 ± 25.67 vs. 30.00 ± 11.19 pg/mL; p = .002) and IFN-γ (65.70 ± 39.78 vs. 32.14 ± 17.48 pg/mL; p = .001) were significantly higher in the seroconverter group compared to non-seroconverter. In contrast, TGF-ß (820.96 ± 415.78 vs. 1045.57 ± 204.66; p = .046) was higher in non-seroconverter. CONCLUSIONS: Pro-inflammatory cytokines IL-6 and IFN-γ were significantly associated with seroconversion after SARS-CoV-2 infection and vaccination in RTRs.