CHAT and infection: Although leukocyte-derived ACh effects in the spleen have been shown to require T cell-mediated ACh51,52, T cell-specific deletion of ChAT (Chatfl/fl-LckCre+/−) did not affect influenza virus loads at this time (Fig. 3i), consistent with their low frequencies before infection (Extended Data Fig. 2) and also consistent with B cells remaining the predominant population of ChAT-GFP+ cells at early infection time points (Extended Data Fig. 5a–e).