In this issue

It is with great sadness that we publish an obituary to a most distinguished member of our Editorial Board, Professor Yoji Iikura. He was a very good friend and colleague. His contributions to our discipline and our Journal have been outstanding. I believe that he took great pride in his association with Pediatric Allergy & Immunology and I think he would have been very happy with this Issue which is dedicated to him. It is always a great pleasure to publish review articles from distinguished colleagues, and a collaboration between Andrew Kemp from Melbourne and Bengt Björkstén from Stockholm further reviews the epidemiological evidence for the hygiene hypothesis particularly as it impacts on early life. Their conclusion is that key environmental influences are likely to be operative throughout life rather than just as an early life phenomenon. The challenge is now to address all of the seven criteria they list to fully address the hypothesis. Andrew Kemp is again involved with our second paper which is based on a very large prospective birth cohort from Northern Tasmania in Australia. This study also addresses the hygiene hypothesis in contrasting family size with specific allergen sensitizations. They show an effect of larger family size on rye grass sensitivity but not house dust mite. This, to a significant extent, is consistent with the original birth order study from David Strachan when the hypothesis was first suggested in 1989. This showed an association between a birth order and hay fever (1). Indeed, the most compelling evidence for a role for the hygiene hypothesis based on a review of the overall literature is in relation to seasonal allergy. A collaboration between Northern Sweden and Professor Tom PlattsMills and his team in Charlottesville, USA, further elaborates on the different influences on specific sensitizations and disease manifestations. Thus sensitization to birth pollen is associated with the highest risk for rhinitis and eczema, whereas sensitivity to dog and horse is associated with a higher risk of asthma. In this Northern Swedish community, house dust mite and mould allergy are very rare problems. Continuing the spirit of international collaboration, our next paper is between Lund in Sweden and Sydney, Australia. It provides convincing evidence that children sensitized to alternaria moulds have an increase in symptoms of rhinoconjunctivitis when the spore counts are high. Remarkably hitherto, there has been relatively little evidence that this is the case. Many groups, including my own, have an interest in the ontogeny of immune responses in fetal life. As such, we monitor cord blood mononuclear cell cytokine profiles. It is, therefore, important to know whether method of birth has any impact on profiles. Marilyn Halonen’s group from Tuscon, Arizona, has shown that the production of IFN-c and IL-12 by stimulated cord blood mononuclear cells from vaginally delivered babies is higher than those from elective cesarean section deliveries. The stress of a normal delivery clearly has some important priming effects on Th-1 activity. The key question now to answer is whether allergy is more common in babies born by elective section, and if not, why not? Indeed, the Dutch group show in their paper that infants who wheeze in the first year of life have increased IL-10 to IL-12 ratios. It remains to be seen whether these children will go on to have established atopic asthma. No doubt we will hear more about this cohort in the future. As one might expect from the study from Northern Sweden, sensitization to pollens is likely to be predictive of subsequent seasonal allergic rhinitis. This has proved to be the case in a study from Munich, Germany. Skin prick tests and RAST gave very similar negative predictive values but positive predictive value was marginally better for skin tests than RAST. This reinforces my own prejudice that well performed skin prick tests should remain the mainstay of allergy diagnosis. Over the years, we have published a number of papers on the clinical value of the measurement of serum eosinophil cationic protein. Unfortunately, there are a number of Pediatr Allergy Immunol 2003: 14: 72–73