ISOLATION AND CHARACTERIZATION OF 2 CDNA CLONES CODING FOR ISOFORMS OF THE PARIETARIA-JUDAICA MAJOR ALLERGEN PAR-J-1.0101

Two cDNA clones named P9 and P1* of 794 and 631 bp, respectively, wer e isolated from a lambda ZAP cDNA expression library using Parietaria judaica (Pj) pollen-specific IgE antibodies from a pool of sera (n = 2 3) of patients allergic to Pj. Sequence analysis showed open reading f rames of 176 and 138 amino acids. Both clones contain a putative signa l peptide giving two mature processed proteins named Par j 1.0102 of 1 4,726 D and Par j 1.0201 of 10,677 D. These proteins represent isoalle rgenic forms of the major Pj allergen Par j 1.0101 (clone P5) previous ly reported. The Par j 1.0102 shared 98% amino acid sequence homology with the P5, while the Par j 1.0201 shared 89% homology. Since P1, P5 and P9 clones were expressed in Escherichia coli, and since the three allergenic proteins shared a very high degree of sequence identity and comparable binding to the Pj-specific IgE, we decided to analyze in m ore detail the immunological properties of only one allergen, the reco mbinant Par j 1.0101. The allergenic activity determined by the histam ine release assay ranged between 9 and 56%, depending on the allergic patient analyzed, while it blocked approximately 40% of all the Pj-spe cific IgE antibodies, as detected after ELISA and cross-absorption ana lysis.