Assessment of 4 Doses of SARS-CoV-2 Messenger RNA–Based Vaccine in Recipients of a Solid Organ Transplant

International audienceThis case series study assesses whether a fourth dose of a SARS-CoV-2 messenger RNA (mRNA)–based vaccine is associated with improved anti–SARS-CoV-2 antibody response in solid organ transplant recipients in France

Circulating follicular helper T cells exhibit reduced ICOS expression and impaired function in narcolepsy type 1 patients

International audienceDespite genetic and epidemiological evidence strongly supporting an autoimmune basis for narcolepsy type 1, the mechanisms involved have remained largely unknown. Here, we aimed to investigate whether the frequency and function of circulating follicular helper and follicular regulatory T cells are altered in narcolepsy type 1. Peripheral blood mononuclear cells were collected from 32 patients with narcolepsy type 1, including 11 who developed disease after Pandemrix® vaccination, and 32 age-, sex-, and HLA-DQB1*06:02-matched healthy individuals. The frequency and phenotype of the different circulating B cell and follicular T cell subsets were examined by flow cytometry. The function of follicular helper T cells was evaluated by assessing the differentiation of naïve and memory B cells in a co-culture assay. We revealed a notable increase in the frequency of circulating B cells and CD4+CXCR5+ follicular T cells in narcolepsy patients compared to age-, sex- and HLA-matched healthy controls. However, the inducible T-cell costimulator molecule, ICOS, was selectively down-regulated on follicular T cells from patients. Reduced frequency of activated ICOS+ and PD1high blood follicular T cells was also observed in the narcolepsy group. Importantly, follicular T cells isolated from patients with narcolepsy type 1 had a reduced capacity to drive the proliferation/survival and differentiation of memory B cells. Our results provide novel insights into the potential involvement of T cell-dependent B cell responses in the pathogenesis of narcolepsy type 1 in which down-regulation of ICOS expression on follicular helper T cells correlates with their reduced function. We hypothesize that these changes contribute to regulation of the deleterious autoimmune process after disease onset

Humoral and Cellular Immune Responses of Solid Organ Transplant Patients on Belatacept to Three Doses of mRNA-Based Anti-SARS-CoV-2 Vaccine

International audienceBackground: Two doses of anti-SARS-CoV-2 mRNA-based vaccines are poorly immunogenic in solid organ transplant recipients (SOT). Methods: In total, 68 belatacept-treated SOT recipients followed at the Toulouse University Hospital were investigated. They were given three injections of the BNT162b2 mRNA COVID-19 vaccine. Their humoral response was assessed by determining anti-spike antibodies and neutralizing antibodies. The T-cell responses were assessed using an enzyme-linked immunospot assay that measured the interferon-γ produced by specific SARS-CoV-2 T-cells in a subgroup of 17 patients. Results: Only 23.5% of these patients developed a detectable anti-spike response. Moreover, the cellular and the humoral responses were well correlated. Patients with no humoral response were also without a detectable cellular response. Those belatacept-treated patients who developed an anti-SARS-CoV-2 humoral response were younger, had been transplanted for longer, and had a higher lymphocyte count and a better glomerular filtration rate than those with no response. Finally, patients on tacrolimus plus belatacept produced a lower immune response. Conclusions: Belatacept-treated SOT recipients have a reduced immune response to anti-SARS-CoV-2 mRNA vaccination. The vaccine should be given quite separately from the belatacept infusion to improve immunogenicity. Studies to assess whether switching to another immunosuppressive regimen can improve the post-vaccination immune response would be useful

Humoral and Cellular Immune Responses of Solid Organ Transplant Patients on Belatacept to Three Doses of mRNA-Based Anti-SARS-CoV-2 Vaccine

Background: Two doses of anti-SARS-CoV-2 mRNA-based vaccines are poorly immunogenic in solid organ transplant recipients (SOT). Methods: In total, 68 belatacept-treated SOT recipients followed at the Toulouse University Hospital were investigated. They were given three injections of the BNT162b2 mRNA COVID-19 vaccine. Their humoral response was assessed by determining anti-spike antibodies and neutralizing antibodies. The T-cell responses were assessed using an enzyme-linked immunospot assay that measured the interferon-γ produced by specific SARS-CoV-2 T-cells in a subgroup of 17 patients. Results: Only 23.5% of these patients developed a detectable anti-spike response. Moreover, the cellular and the humoral responses were well correlated. Patients with no humoral response were also without a detectable cellular response. Those belatacept-treated patients who developed an Anti-SARS-CoV-2 humoral response were younger, had been transplanted for longer, and had a higher lymphocyte count and a better glomerular filtration rate than those with no response. Finally, patients on tacrolimus plus belatacept produced a lower immune response. Conclusions: Belatacept-treated SOT recipients have a reduced immune response to anti-SARS-CoV-2 mRNA vaccination. The vaccine should be given quite separately from the belatacept infusion to improve immunogenicity. Studies to assess whether switching to another immunosuppressive regimen can improve the post-vaccination immune response would be useful