New technologies and applications in infant B cell immunology

•New immune monitoring technologies enable sample-sparing analysis of infant specimens.•Differences between infant and adult immune responses remain underexplored.•Infant neutralizing antibodies can be potent without high somatic mutation levels. The human immune system changes dramatically with age, and early life exposures to pathogens and environmental antigens begin the formation of immune memory which influences subsequent responses later in life. To study infant immunity, sample-sparing experimental methods that extract maximal data from small samples of blood or other tissues are needed; fortunately, recent developments in high-throughput sequencing and multiplexed labeling and measurement of markers on cells are well-suited to these tasks. Here, we review some recent studies of infant immune responses to infectious disease, highlighting similarities and differences between infants and adults, and identifying important questions for future research. Recent clinical trials in food allergy have revealed the critical role of immunological events in the first year of life that determine an individual’s risk of developing peanut allergy; these also warrant thorough evaluation using the new immune monitoring tools.