Chemical and immunologic study of pollen from the gramineous plant Lolium perenne
Alonso, A.; Mouchian, K.; Rodríguez, S.; Scavini, L.; Pionetti, C.H.
Allergologia et Immunopathologia 11(5): 347-359
1983
ISSN/ISBN: 0301-0546 PMID: 6660173 Document Number: 199613
In order to study the chemical composition and immunologic reactivity of an extract of rye grass pollen (RGP), aliquots of this antigen were passed through Sephadex G-50 and DEAE-cellulose ion-exchange columns. This method yielded 7 proteins and 10 sugars, whose quantities were determined by absorbance in a LKB Uvicrd spectrophotometer at 280 nm and 470 nm respectively. Protein contents were also recorded by the Lowry method and the micro-Kjehldal technique. Adult albino rabbits were immunized with a mixture of RGP and complete Freund's adjuvant over a period of eight weeks. The antisera obtained were studied by the Ouchterlony method and the passive hemagglutination technique against RGP and all the eluated fractions. Skin tests with RGP and its fourteen most conspicuous eluated fractions were performed in 29 untreated atopic patients with seasonal rhinitis and bronchial asthma, high reactivity to a whole grass mixture and RGP and high levels of serum IgE. Results were recorded after 15 minutes for the immediate reaction when the histamine positive control had reached near maximal size and in the morning. Molecular weights were studied with the usual marker proteins subjected to gel filtration by a Sephadex G-50 column. Each protein concentration was 13,5 mg/ml in a volume of 1,5 ml, meanwhile RGP was 12 mg/ml. PRIST and RAST were carried out with human sera to determine IgE levels and specific IgE and IgG anti-RGP antibodies. Ouchterlony showed precipitin lines among the rabbit RGP-antiserum, whole grass mixture, RGP and the fractions from tubes 38 and 359, meanwhile Boyden's technique appeared positive only between the anti-serum and whole grass mixture and RGP (1:256). The other fractions gave negative results as all of the human sera of both groups. Skin tests in the atopics showed type I reactions with whole grass mixture, RGP, proteins no 33 (Sephadex), 25 and 38 (DEAE-cellulose) and sugars no 56, 192 and 360, but negative results in the controls. Molecular weights obtained were for fraction no 13 68.000, for fraction no 28 25.500 and for fraction no 33 18.400 daltons respectively. RAST revealed in 28 sera a IgG anti-RGP before hyposensitization therapy and an IgE anti-RGP of class 2 only in 8 sera and in 10 of class 1. This surprising result needs further investigation to clarify if the ratio IgE/IgG anti-RGP plays any role in the pathogenesis of pollinosis.