Identifying Cross-Reactive Pollen Allergens : An Empirical Approach

Abstract

Twenty airborne pollen grains and fungal spores prevalent in the air during February to June in and around Kolkata, India were found to have caused most of the allergy related respiratory illness among 100 atopic paients who visited the allergy clinic of the Institute of Child Health, Kolkata. They were subjected to the skin prick tests(SPT) using extracts from the allergens selected in accordance with the patient's history.

Strongly cross­reactive allergens are expected to show similar reactions with respect to wheal diameters when applied to a given patient. An exploratory data analysis of wheal diameters is proposed to discover the groups of cross reactive allergens.

Cluster analysis of wheal diameters is carried out to identify the groups of cross reactive allergens. It is well known that the same data set may produce altogether different clusters if different clustering methods are applied or different measures of dissimilarities are used. As such the clusters produceed by a single method and a single measure of dissimilarity cannot be relied upon. There always is a chance of false discovery of crqss­reactive allergens in an approach like this. Keeping this in view three clustering methods each with two dissimilarity measures are applied on the same SPT data set. The relative frequency of occurrence of a cluster is taken as a measure of confidence on the inference.

Four clusters of strongly cross­reactive allergens are identified among the twenty pollen allergens considered.

Identification of the of cross­reactive pollen allergens by using an empirical approach proposed in this paper may help the doctors in the allergy clinic to decide on the doses and number of pollen extracts to be used for immunotherapy. Such an approach results in considerable savings of time and cost. Also the discovery of groups of cross­reactive pollen allergens by such an empirical method may serve as a putative hypothesis for the medical researchers to be confirmed by biochemical experiments.