Modulation of the IgE Antibody Response in Rats to Kentucky Blue Grass Pollen Allergens

Abstract

The low molecular weight dialyzable fraction (D) prepared from the aqueous extract of Kentucky Blue Grass pollen was shown to suppress the formation of IgE antibodies in rats immunized with the nondialyzable fraction (R). In an attempt to establish the nature of the constituents responsible for this suppression, D was fractionated by gel filtration through Sephadex G-25. The first fraction eluted (D_I) elicited skin reactions in rats sensitized with a rat reaginic serum to R and also gave a precipitate with a rabbit antiserum to R. A later fraction (D_III) was devoid of these two properties. To investigate the effects of these fractions on the antibody response, rats received either D_I or D_III, administered in saline, prior to their immunization with R in presence of aluminum hydroxide. Pretreatment with D_I resulted in a reduction of IgE antibody levels as compared with the IgE antibody response in control animals which had received pretreatment only with saline; however, pretreatment with D_I did not affect the anti-R-hemagglutinating titers. In contrast, pretreatment with D_III enhanced both the IgE and the hemagglutinating antibodies. Hence, it is concluded that the composite fraction D contains one group of constituents capable of suppressing and another of enhancing the IgE antibody response.

Preferential Synthesis of IgE Reaginic Antibodies in Rats Immunized with Alum-Adsorbed Antigens

“…However, heating of the reaginic sera (OA, DWSR and DWST) at 56 °C for 4 h or coprecipitation of rat antisera with a rabbit antiserum specific for rat myeloma IgE (kindly supplied by Dr. A. Froese, Uni versity of Manitoba, Winnipeg, Manitoba) according to the method of Conrad and Froese [3] completely abolished the reaginic activity of 2-, 4-and 48-hour PCA reac tions. These results support those of our earlier studies [16,17] and other investiga tors [4,12] who reported that it is extremely difficult to obtain an IgGa response with al um-precipitated antigens. However, Murphey et al [9] observed both IgE (a 48-hour PCA titer prior to heating of 128) as well as IgGa (a 2-hour PCA titer after heating at 56 °C for 1 h of 128) antibodies against OA in outbred Wistar rats using essentially the same method we described here.…”

Isolation of Allergenically Active Cytochrome c from Kentucky Blue Grass Pollen

“…This procedure was employed to establish the PCA activity of isolated fractions relative to that of R. For this purpose, IgE antibodies to the aller gens present in R were produced in mice and were determined in terms of their PCA titer on the skin of rats, as previously described (8,9]. For the ac tual determination of PCA activity, hooded rats were locally sensitized by the intradermal injec tion of a volume of 50 «1 of the mixture and 24 h later the PCA reaction, if any, was elicited by intraveneous (i.v.)…”

Isolation of a Low Molecular Weight Constituent from Kentucky Blue Grass Pollen Possessing Carrier Activity of High Molecular Weight Constituent(s)

“…used in the initial phase of this study were pre pared as previously described [3,5]. However, the original method for the isolation of C-I-3 was sub stantially modified as outlined below.…”

“…It was recently shown in this laboratory [3,4) that intraperitoneal immunization of rats and mice with the nondialyzable frac tion of the aqueous extract of Kentucky Blue Grass pollen (KBG aq.ext. ), referred to as the reténtate (R), in the presence of alu minum hydroxide, resulted in the formation of anti-R IgE antibodies.…”

“…isolated by gel chromatography from the dialysate of KBG aq. ext., con tained components which were capable of suppressing both rat [3] and murine [4] IgE antibody responses to R, when D-I was ad ministered intraperitoneally prior to immu nization with R. Fraction D-I had been fur ther separated by ion-exchange chromato graphy and gel filtration into three fractions [5] and one of these, C-I-3, having an esti mated molecular weight of 4,800 daltons, was deemed to be devoid of determinants responsible for the allergenic activity of R, since it neither inhibited the binding of hu man anti-KBCi IgE antibodies to allcrgosorbent discs prepared with R nor triggered passive cutaneous anaphylaxis (PCA) in skin sites of hooded rats sensitized with mu rine or rat reaginic antibodies to R.…”