Analysis of T-cell reactive regions and HLA-DR4 binding motifs on the latex allergen Hev b 1 (rubber elongation factor).
BACKGROUND
The rubber elongation factor in Hevea rubber (Hev b 1) is one of the important latex-allergenic proteins inducing the production of specific IgE antibodies in latex-exposed subjects. In addition, Hev b 1 induces lymphocyte proliferation responses. A study about detailed T-cell epitope analysis of major latex allergens has not been published yet.


OBJECTIVE
The aim of this study was to define the T-cell reactive regions on the latex allergen Hev b 1.


METHODS
Nine overlapping peptides with 19 or 17 amino acid lengths representing the complete sequence of Hev b 1 were used for T-cell epitope mapping. Peripheral blood mononuclear cells (PBMCs) of latex-sensitized patients and healthy subjects were isolated and stimulated with the synthetic peptides to determine the specific proliferation response. The examined patients were sensitized to latex by occupational exposure (n=14) and suffered from rhinitis, conjunctivitis, contact urticaria and/or asthma. Two control groups of non-sensitized subjects were studied, one occupationally exposed to latex (n=4), the other one not exposed to latex (n=4).


RESULTS
Positive proliferation response induced by one or more peptides was detected in 10 of the latex-sensitized patients and in two of the latex-exposed non-sensitized subjects. Each patient exhibited an individual epitope reactivity pattern. The whole protein was found to be immunogenic, but the intensity of lymphocyte responses induced by the peptides was different. The majority of the patients' PBMCs (more than 66%) responded to the peptides 31-49 and 91-109. Using the peptide selection of Stille's algorithms, three epitopes were predicted covering region 38-74 and two others covering region 82-104; the two peptides 31-49 and 91-109 are part of these regions. A strong HLA-DR4Dw4 (DRB1*0401)-binding motif according to published DR4w4 binding motifs was predicted in the region of 102-110 including peptide 91-109 to which the majority of tested HLA-DR4-positive patients responded.


CONCLUSIONS
Our data indicate that the whole 14 kDa protein Hev b 1 is immunogenic having regions that demonstrate individual and varying PBMC stimulation. Experimental data of T-cell reactive regions based on PBMC-stimulation complement the information on T-cell epitope prediction. In addition, the Hev b 1 molecule contains a HLA-DR4Dw4 (DRB1*0401)-binding motif.
Raulf-Heimsoth
M
M
Research Institute for Occupational Medicine (BGFA), Ruhr-University Bochum, Germany.
Chen
Z
Z
Rihs
H P
HP
Kalbacher
H
H
Liebers
V
V
Baur
X
X
D000328:Adult; D000485:Allergens; D000595:Amino Acid Sequence; D000918:Antibody Specificity; D052179:Antigens, Plant; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte; D005260:Female; D006681:HLA-D Antigens / Q000276:immunology; D015804:HLA-DR4 Antigen / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity; D016056:Immunodominant Epitopes; D007073:Immunoglobulin E / Q000097:blood; D007840:Latex / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016273:Occupational Exposure; D010940:Plant Proteins; D011506:Proteins / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D000485:Allergens; D052179:Antigens, Plant; D018984:Epitopes, T-Lymphocyte; D006681:HLA-D Antigens; D015804:HLA-DR4 Antigen; C053495:HLA-Dw4 antigen; D016056:Immunodominant Epitopes; D007840:Latex; D010940:Plant Proteins; D011506:Proteins; C061477:REF protein, Hevea brasiliensis; D007073:Immunoglobulin E