PODOCARPUS-GRACILIOR AND CALLITRIS-VERRUCOSA - NEWLY IDENTIFIED ALLERGENS THAT CROSS-REACT WITH CUPRESSUS-SEMPERVIRENS

Thirty-six symptomatic patients, with positive skin reactions to Cupre ssus sempervirens pollen extract were skin-tested with pollen extracts of Podocarpus gracilior and Callitris verrucosa, of these 17 (47%) ha d positive responses to P. gracilior, nine (25%) to C. verrucosa, and six (17%) to both. None of the non-atopic healthy controls had positiv e reactions to either of the extracts. Radioallergosorbent test (RAST) -inhibition studies were performed with pooled sera from three patient s. Fifty per cent inhibition was obtained with 11 mu g protein of C. s empervirens, 54 mu g of P. gracilior, and 71 mu g of C. verrucosa; how ever, when pollen extract of Olea europaea, an unrelated allergen, was tested, 265 mu g protein were needed to obtain 50% inhibition. One-di mension sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS -PAGE) analysis of pollen extracts from the three species revealed tha t they had several very similar protein bands. Using Western blot anal ysis, several closely related IgE binding proteins were identified in the three species. It was concluded that the pollen grains of P. graci lior and of C. verrucosa are potentially allergenic. The presence of c ommon allergenic proteins indicate partial crossreactivity with C. sem pervirens.