Toll-like receptor 7/8 agonist stimulation rapidly skews the antibody repertoire of B cells in non-human primates.

Introduction: Toll-like receptors 7 and 8(TLR7/8) recognize purine-rich single-stranded RNA from pathogens, triggering immune responses. Although TLR7/8 agonists are emerging as potential novel adjuvants, their impact on the adaptive B cell response, particularly antibody repertoire, remains unclear. Methods: Six Indian rhesus macaques(IRMs) and six African green monkeys(AGMs) were stimulated with a TLR7/8 agonist. Peripheral blood samples were collected pre-stimulation and multiple timepoints within one week post-stimulation for flow cytometry and antibody repertoire sequencing. Results: B cell activation was observed at 24 hours. Significant increases in antibody repertoire diversity were detected at 48 and 72 hours in both species; however, diversity remained elevated at one week in IRMs but returned to baseline in AGMs. Analysis of antibody lineage distributions revealed a marked increase in increased lineages at 48 and 72 hours, characterized by higher frequency, a greater number of antibody clonotypes, and increased mutation rates. The identified expanded lineages, induced by the TLR7/8 agonist, exhibited λ chain bias and divergent antibodies across individuals, and primarily originated from highly mutated antibodies, likely corresponding to memory/effector-like B cells. Conclusions: Our findings demonstrate that the TLR7/8 agonist rapidly induces a divergent expansion of B cells, establishing an immune foundation supporting vaccine responses and offering new insights into the dynamic B cell modulation.