Identification of IgE and IgG binding epitopes on beta- and kappa-casein in cow's milk allergic patients.
BACKGROUND
Cow's milk allergy (CMA) affects 2.5% of children aged less than 2 years of age. Although beta- and kappa-casein are considered among the major allergens responsible for CMA, no data are available on their allergenic epitopes in humans.


OBJECTIVE
The aim of the study was to identify IgE- and IgG-binding epitopes on beta- and kappa-casein and to determine whether the pattern of epitope recognition is associated with the natural history of CMA.


METHODS
Overlapping decapeptides representing the entire length of beta- and kappa-casein, respectively, were synthesized on a cellulose-derivatized membrane. Sera from 15 milk-allergic children, 4-18 years of age, with high levels of specific IgE antibodies to cow's milk were used to identify IgE- and IgG-binding epitopes. In addition, IgE epitopes were screened with pooled or individual sera from younger patients aged less than 3 years and who had low levels of specific serum IgE, who are likely to outgrow CMA.


RESULTS
Six major and three minor IgE-binding epitopes, as well as eight major and one minor IgG binding regions, were identified on beta-casein. Eight major IgE-binding epitopes, as well as two major and two minor IgG-binding epitopes, were detected on kappa-casein. Three of the IgE binding regions on beta-casein and six on kappa-casein were recognized by the majority of patients in the older age group, but not by the younger patients.


CONCLUSIONS
Information regarding the immunodominant epitopes in beta- and kappa-casein may be important for understanding the pathophysiology and natural history of CMA. Differences in epitope recognition may be useful in identifying children who will have persistent milk hypersensitivity.
Chatchatee
P
P
Division of Paediatric Allergy & Immunology, Jaffe Institute for Food Allergy, The Mount Sinai Medical Center, New York, NY, USA.
Järvinen
K M
KM
Bardina
L
L
Vila
L
L
Beyer
K
K
Sampson
H A
HA
D000293:Adolescent; D000595:Amino Acid Sequence; D000818:Animals; D001666:Binding Sites, Antibody; D002364:Caseins / Q000276:immunology* / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D000939:Epitopes / Q000378:metabolism*; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000378:metabolism*; D007074:Immunoglobulin G / Q000097:blood / Q000378:metabolism*; D008297:Male; D008892:Milk / Q000276:immunology* / Q000378:metabolism; D016269:Milk Hypersensitivity / Q000097:blood / Q000276:immunology*; D008969:Molecular Sequence Data
D002364:Caseins; D000939:Epitopes; D007074:Immunoglobulin G; D007073:Immunoglobulin E