Multiple Amb a I allergens demonstrate specific reactivity with IgE and T cells from ragweed-allergic patients.
The relationship between the structure and abundance of an inhaled protein and its potential for causing an allergic response is unknown. This study analyzes Amb a I, a family of related proteins formerly known as Ag E, that comprise the major allergens of short ragweed (Ambrosia artemisiifolia). T cells isolated from ragweed allergic patients were shown to proliferate in response to purified Amb a I.1 protein from pollen in in vitro secondary cultures, demonstrating the presence of T cell stimulatory epitopes in Amb a I.1. Three recombinant forms of Amb a I (Amb a I.1, Amb a I.2, and Amb a I.3) obtained as cDNA derived from pollen mRNA were expressed in bacteria. All three recombinant forms were shown to be specifically recognized by pooled ragweed-allergic human IgE on immunoblots, confirming these gene products are important allergens. An examination of immunoblots probed with sera derived from allergic patients revealed a variation in IgE binding specificity. A minority of patients' IgE exclusively reacted with recombinant Amb a I.1, whereas most patients' IgE reacted with Amb a I.1 as well as Amb a I.2 and Amb a I.3 proteins. A detailed examination of the reactivity of T cells derived from 12 allergic patients to these recombinant Amb a I forms revealed that these allergens are all capable of stimulating T cell proliferation in in vitro assays. It is concluded that the allergic response to ragweed pollen in most allergic patients is composed of a reaction to multiple related Amb a I proteins at both the B and T cell levels.
Bond
J F
JF
ImmuLogic Pharmaceutical Corporation, Cambridge, MA 02139.
Garman
R D
RD
Keating
K M
KM
Briner
T J
TJ
Rafnar
T
T
Klapper
D G
DG
Rogers
B L
BL
D000485:Allergens / Q000032:analysis / Q000276:immunology*; D002478:Cells, Cultured; D000939:Epitopes / Q000032:analysis; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology; D011058:Pollen / Q000032:analysis; D011994:Recombinant Proteins / Q000032:analysis; D006255:Rhinitis, Allergic, Seasonal / Q000209:etiology / Q000276:immunology* / Q000628:therapy; D013601:T-Lymphocytes / Q000276:immunology*
D000485:Allergens; D000939:Epitopes; D010940:Plant Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E