Colostrum is required for the postnatal ontogeny of small intestine innate lymphoid type 2 cells and successful anti-helminth defences

To the Editor,
Colostrum is the physiological food for the first 72 h of a newborn. Its window of intake and high content in microbiota-shaping and growth factors suggest that colostrum is critical in guiding gut immune development. To address this hypothesis, we developed a mouse model of colostrum deprivation (Figure 1A). Like humans, mice have different lactation stages. We compared pups nursed immediately after birth by dams that no longer produced colostrum (Day 9 of lactation, a well-defined lactation stage in mice that is distinct from colostrum) with control pups. This allowed us to assess the causal role of colostrum in the perinatal expansion of two cell types important in gut immune regulation, namely ILCs and CD4+ T cells...