11238. T cell response



さらには、viral loadにも差が無いと。(まぁ、これはそんなもんだと)





In our cohort, we observed an increase in TCR signaling and T cell activation gene expression in adults compared to children with asymptomatic to mild SARS-CoV-2. This finding may represent increased TCR signaling and activation in the setting of cross-reactive T cells. Such cross-reactive memory T cells have been reported for SARS-CoV [60] and recently for SARS-CoV-2[61– 65]. This observation initially led to speculation that these cross-reactive antibodies and T cells could play a protective role in children and young adults and that vanishing adaptive immunity would make elderly individuals more susceptible to SARS-CoV-2. However, in another study, a larger number of SARS-CoV-2 cross-reactive memory T cells was observed in the elderly and patients with severe compared with mild COVID- 19[65]. Importantly, these cross-reactive T cells exhibited lower avidity and reduced antiviral responses when stimulated with SARS-CoV-2 peptides compared with T cells from patients who recovered from COVID-19. Thus, instead of being protective, these cross-reactive, low-avidity T cells, which are less efficient at virus elimination, could contribute to prolonged inflammatory signaling. This hypothesis is attractive as it explains the differences in the epidemiology of SARS-CoV-2, which disproportionately affects elderly individuals. Children and young adults, who likely have fewer lifetime coronavirus exposures, often have only mild symptoms, despite having viral loads in the upper airways comparable to adults[3,14].


Age-related Differences in the Nasal Mucosal Immune Response to SARS-CoV-2

60. Gioia C, Horejsh D, Agrati C, Martini F, Capobianchi MR, Ippolito G, et al. T-Cell response profiling to biological threat agents including the SARS coronavirus. Int J Immunopathol Pharmacol. 2005;18: 525–530.

  1. Grifoni A, Weiskopf D, Ramirez SI, Mateus J, Dan JM, Moderbacher CR, et al. Targets of T Cell Responses to SARS-CoV-2 Coronavirus in Humans with COVID- 19 Disease and Unexposed Individuals. Cell. 2020;181: 1489–1501.e15.
  2. Le Bert N, Tan AT, Kunasegaran K, Tham CYL, Hafezi M, Chia A, et al. SARS- CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls. Nature. 2020. doi:10.1038/s41586-020-2550-z
  3. Mateus J, Grifoni A, Tarke A, Sidney J, Ramirez SI, Dan JM, et al. Selective and cross-reactive SARS-CoV-2 T cell epitopes in unexposed humans. Science. 2020 [cited 5 Aug 2020]. doi:10.1126/science.abd3871
  4. Braun J, Loyal L, Frentsch M, Wendisch D, Georg P, Kurth F, et al. SARS-CoV-2- reactive T cells in healthy donors and patients with COVID-19. Nature. 2020;587: 270–274.
  5. Bacher P, Rosati E, Esser D, Martini GR, Saggau C, Schiminsky E, et al. Low avidity CD4+ T cell responses to SARS-CoV-2 in unexposed individuals and humans with severe COVID-19. Immunity. 2020;0. doi:10.1016/j.immuni.2020.11.016