Donor-specific anti-hla alloantibody in kidney transplant recipients with COVID-19 exhibit a different immunoglobulin class and subclass profile when compared to anti-SARS-CoV-2 antibodies

ABSTRACT

Purpose: Both anti-HLA and anti-SARS-CoV-2 antibodies target protein antigens. The aim of the present study was to compare the class and subclass profile of such antibodies in a cohort of kidney transplant patients. Methods: We detected and identified anti-HLA and anti-SARS-CoV-2 antibody in 48 kidney transplant recipients who were hospitalized for SARS-CoV-2 PCR+ infection. Anti-HLA antibodies were detected by single-antigen bead Luminex assay, with IgG class, and IgG1-2-3-4 subclass secondary antibody. Anti-SARSCoV- 2 antibodies were also detected by Luminex assay directed against 5 distinct viral epitopes including the nucleocapsid protein as well as multiple regions of the spike protein. The secondary antibodies addressed total IgG, IgG1-2-3-4, IgM and IgA class/subclasses. Results: The antibody profile (Table 1) included 12/48 cases of donor-specific anti- HLA antibodies, and 43/48 cases with anti-SARS-CoV2 antibodies. The majority of HLA-specific antibodies targeted HLA-DQ, with a dominant IgG class and an IgG1+IgG2+IgG3 subclass prevalence. However, anti-SARS-CoV2 antibody profile was characterized by increased prevalence of IgM (38/43, 79%) and IgA (41/42, 85%), and a lower prevalence of IgG2. Conclusions: Overall, these data suggests that kidney transplant recipients with Covid-19 exhibit a humoral immune response both to donor-HLA and SARS-CoV-2. Although both are protein antigens, the allo-immune response has a high-IgG/low IgA pattern, while the Covid-19 antibody profile includes high IgA. Additional follow-up is needed to determine if the increased IgA is a consistent marker of anti-SARS-CoV-2 antibody response. (Table Presented).