EFFECTS OF EXPOSURE TO CAT AND TO BREAST MILK ON DEVELOPMENT OF ASTHMA: NEW EVIDENCE ON OLD DILEMMAS

Key words: Breastfeeding, Cat, Asthma, Immunological balance

A series of cross sectional and prospective studies have shown that, differently from older beliefs, early exposure to cat has a protective effect on the development of allergy and asthma in adult age. This effect, which is true for high and low concentration of cat antigens but not for the intermediate ones has two possible explanations: the induction of tolerance or the coexistence of cat allergens with bacterial endotoxins which are able to shift the immunological balance towards Th1 response. Recent studies have also shown that breastfeeding is associated to higher risk of developing allergy and asthma in adult life, but this evidence is conflicting with protective effects shown in the first years of life. The biological rationale of these conflicting effects is still obscure.