HOW FAR CAN WE SIMPLIFY IN-VITRO DIAGNOSTICS FOR GRASS-POLLEN ALLERGY- A STUDY WITH 17 WHOLE POLLEN EXTRACTS AND PURIFIED NATURAL AND RECOMBINANT MAJOR ALLERGENS

Background: Current diagnostics for grass pollen allergy are composed of mixtures of pollen of different grass species. Their complex compos ition hampers accurate standardization. Objective: The aim of the stud y was to investigate whether mixtures of grass pollen extracts can be replaced by a single pollen species and whether a single pollen specie s can be replaced by a limited number of purified natural or recombina nt major allergens, Methods: Sera (n = 800) were selected on the basis of a general suspicion for inhalant allergy and tested in a RAST for IgE reactivity with pollen from 17 different grass species. Cross-reac tivity of IgE responses was studied by means of RAST inhibition. Sera with positive test results for grass pollen were tested in a RAST for natural Lol p 1 and Lol p 5 and recombinant Phl p 1 and Phl p 5. Resul ts: Specific IgE antibodies against one or more of the 17 pollen speci es were detected in 209 of 800 sera (26.1%). The highest responses wer e observed against Poa pratensis followed by Festuca rubra, Phleum pra tense, and Dactylis glomerata, IgE responses were clearly lower (appro ximately by a factor of 5) against only three species (Phragmites comm unis, Cynodon dactylon, and Zea mays). With the exception of a few low -responder sera, no sera were found to have negative test results to t he high responder species and positive results to any of the other spe cies. Sera with positive test results for grass pollen (n = 154) were tested with purified Lol p 1 and Lol p 5, IgE anti-Lol p 1 and Lol p 5 accounted for an average of 81% +/- 7% of total anti-grass pollen IgE , For 14 sera (all with low anti-grass pollen IgE titers), a RAST with purified allergens resulted in a false-negative diagnosis for grass p ollen allergy. With recombinant Phl p 1 and Phl p 5, the mean IgE reac tivity was 57% +/- 6% of the anti-grass pollen IgE response (n = 141), with 13 false-negative results. Conclusion: One grass species is suff icient for in vitro diagnosis of grass pollen allergy, With purified n atural Lol p 1 and Lol p 5, greater than 90% of grass-positive sera is detected. Around 80% of the IgE response to grass pollen is directed to these major allergens. Recombinant allergens, produced in Escherich ia coli, did not equal the IgE-binding capacity of their natural count erparts.