Abstract
BACKGROUND: Bronchus-associated lymphoid tissue (BALT) is well characterised in rabbits and rats. In humans, however, it does not seem to be present in the healthy adult lung, although it can develop after certain microbial stimulation. METHODS: In the present study a consecutive series of lungs from 88 children who had died of sudden infant death syndrome (SIDS) and 34 control cases of comparable age were examined for the presence of BALT. RESULTS: BALT was present in 36.4% of the patients who had died of SIDS and in 44.1% of the control cases. The probability of finding BALT increased with age, with similar kinetics in both groups. CONCLUSIONS: Future studies need to define when and at what rate BALT disappears as children get older. In young children BALT may act as an entry site for antigens to initiate an immune response, as is well documented for the gut-associated lymphoid system.