Response to “Need for functional validation of B cell trajectory in transplant tolerance”

Guinn et al. reveal a shift from T cell to B cell dominance with regulatory B cell signatures in accepted allografts in mice. However, single-cell RNA sequencing has limitations in rare transcript detection that may introduce biases. Claims of a T to B cell transition require cautious interpretation. While early B cell infiltration was higher in accepted grafts, whether this is an outcome or driver of tolerance is undetermined.