A glycoprotein from Schistosoma mansoni eggs binds non-antigen-specific immunoglobulin E and releases interleukin-4 from human basophils.
We have recently shown that soluble extracts from Schistosoma mansoni eggs (SmEA) triggered basophils from nonsensitized donors to rapidly release interleukin (IL)-4. Assuming that this mechanism might play a role in vivo in biasing the immune response towards a Th2 phenotype, we determined basic properties of the IL-4-inducing activity contained in SmEA. Sensitivity to pepsin digestion indicated protein nature. Binding to and specific elution from Concanavalin A-sepharose suggested that this protein contains mannose residues, thus being a glycoprotein. The IL-4-inducing activity was stable for 30 min at room temperature towards shifting the pH between 3 and 10. When incubated at 100 degrees C, it was stable at pH 3, but less stable at neutral and alkaline pH. Electroelution from an SDS-PAGE gel indicated an apparent molecular weight of the IL-4-inducing activity between 31 and 66 kDa. Although binding to purified human immunoglobulin E (IgE) and activating basophils IgE-dependently, SmEA appears to activate basophils in a non-antigen-specific way, since the cells were purified from noninfected donors. Because the IL-4-inducing activity was found to be released from eggs, it could be an important factor in the environment of the eggs skewing the immune response towards the Th2 phenotype.
Haisch
K
K
Department of Microbiology, SUNY at Buffalo, Buffalo, NY, USA.
Schramm
G
G
Falcone
F H
FH
Alexander
C
C
Schlaak
M
M
Haas
H
H
D000818:Animals; D001491:Basophils / Q000378:metabolism*; D003208:Concanavalin A / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D015801:Helminth Proteins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007073:Immunoglobulin E / Q000378:metabolism*; D015847:Interleukin-4 / Q000096:biosynthesis*; D008970:Molecular Weight; D010063:Ovum / Q000737:chemistry / Q000276:immunology; D012550:Schistosoma mansoni / Q000737:chemistry / Q000276:immunology*; D013696:Temperature
D006023:Glycoproteins; D015801:Helminth Proteins; D003208:Concanavalin A; D015847:Interleukin-4; D007073:Immunoglobulin E