VH gene usage in immunoglobulin E responses of seasonal rhinitis patients allergic to grass pollen is oligoclonal and antigen driven.
BACKGROUND
IgE is the pivotal-specific effector molecule of allergic reactions yet it remains unclear whether the elevated production of IgE in atopic individuals is due to superantigen activation of B cell populations, increased antibody class switching to IgE or oligoclonal allergen-driven IgE responses.


OBJECTIVE
To increase our understanding of the mechanisms driving IgE responses in allergic disease we examined immunoglobulin variable regions of IgE heavy chain transcripts from three patients with seasonal rhinitis due to grass pollen allergy.


METHODS
Variable domain of heavy chain-epsilon constant domain 1 cDNAs were amplified from peripheral blood using a two-step semi-nested PCR, cloned and sequenced.


RESULTS
The VH gene family usage in subject A was broadly based, but there were two clusters of sequences using genes VH 3-9 and 3-11 with unusually low levels of somatic mutations, 0-3%. Subject B repeatedly used VH 1-69 and subject C repeatedly used VH 1-02, 1-46 and 5a genes. Most clones were highly mutated being only 86-95% homologous to their germline VH gene counterparts and somatic mutations were more abundant at the complementarity determining rather than framework regions. Multiple sequence alignment revealed both repeated use of particular VH genes as well as clonal relatedness among clusters of IgE transcripts.


CONCLUSIONS
In contrast to previous studies we observed no preferred VH gene common to IgE transcripts of the three subjects allergic to grass pollen. Moreover, most of the VH gene characteristics of the IgE transcripts were consistent with oligoclonal antigen-driven IgE responses.
Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Commercial Road, Melbourne, Vic 3004, Australia. Janet.Davies@med.monash.edu.au
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Davies
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O'Hehir
D000328:Adult; D000485:Allergens / Q000276:immunology*; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D005260:Female; D005803:Genes, Immunoglobulin; D006801:Humans; D007073:Immunoglobulin E / Q000235:genetics* / Q000276:immunology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D006109:Poaceae; D011058:Pollen; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000235:genetics; D006255:Rhinitis, Allergic, Seasonal / Q000235:genetics* / Q000276:immunology; D016415:Sequence Alignment
D000485:Allergens; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D007073:Immunoglobulin E