High-affinity, neutralizing antibodies to SARS-CoV-2 can be made without T follicular helper cells
Jennifer Chen, Ryan D. Chow, Eric Song, Tianyang Mao, Benjamin Israelow, Kathy Kamath, Joel Bozekowski, Winston Haynes, Renata B. Filler, Bridget L. Menasché, Jin Wei, Mia Madel Alfajaro, Wenzhi Song, Lei Peng, Lauren Carter, Jason S. Weinstein, Uthaman Gowthaman, Sidi Chen, Joe Craft, John Shon, Akiko Iwasaki, Craig B. Wilen, Stephanie C. Eisenbarth
Abstract
T follicular helper (T FH ) cells are the conventional drivers of protective, germinal center (GC)–based antiviral antibody responses. However, loss of T FH cells and GCs has been observed in patients with severe COVID-19. As T cell–B cell interactions and immunoglobulin class switching still occur in these patients, noncanonical pathways of antibody production may be operative during SARS-CoV-2 infection. We found that both T FH -dependent and -independent antibodies were induced against SARS-CoV-2 infection, SARS-CoV-2 vaccination, and influenza A virus infection. Although T FH -independent antibodies to SARS-CoV-2 had evidence of reduced somatic hypermutation, they were still high affinity, durable, and reactive against diverse spike-derived epitopes and were capable of neutralizing both homologous SARS-CoV-2 and the B.1.351 (beta) variant of concern. We found by epitope mapping and B cell receptor sequencing that T FH cells focused the B cell response, and therefore, in the absence of T FH cells, a more diverse clonal repertoire was maintained. These data support an alternative pathway for the induction of B cell responses during viral infection that enables effective, neutralizing antibody production to complement traditional GC-derived antibodies that might compensate for GCs damaged by viral inflammation.