A different profile of epitopic dominance in the immunoglobulin G response to bovine betalactoglobulin in lung cancer.
BACKGROUND
The authors previously documented a quantitative defect in the immunoglobulin G (IgG) response toward bovine betalactoglobulin (BLG), the major cow's milk antigen, and antigen p1 of the house dust mite, Dermatophagoides pteronyssinus (Der p1), in patients with lung cancer. In the Der p1 model, the authors documented at the IgG level an epitope specificity that differed between patients with lung cancer (preferential specificity for cryptic epitopes) and healthy control subjects and patients with mite allergy. The current study investigated whether this varying specificity might be extended to the IgG response toward BLG.


METHODS
The authors compared the IgG binding to native BLG (nBLG) and its products of pepsin hydrolysis (dBLG) in a solid-phase enzyme-linked immunosorbent assay (ELISA) using peroxidase-conjugated protein A in 120 patients with lung cancer, 52 patients with chronic obstructive pulmonary disease (COPD) who were closely matched for age, sex, and smoking habits with the patients with cancer, and 120 healthy control subjects (blood donors).


RESULTS
Expressing the ratio between optical densities observed for dBLG and nBLG, respectively, the authors documented two groups: patient with lung cancer with higher levels of binding on dBLG (mean ratio +/- SD, 1.66 +/- 0.26) and healthy control subjects and patients with COPD with similar levels of retention for dBLG and nBLG (mean ratios +/- SD, 1.00 +/- 0.10 and 1.01 +/- 0.07, respectively). Influence of population characteristics could be excluded. The histologic type of cancer and its extent had no influence on the defined ratio.


CONCLUSIONS
These results suggest a preferential recognition of epitopes unmasked by pepsin hydrolysis (cryptic epitopes?) by lung cancer IgG, contrasting with the preferential specificity of IgG from healthy control subjects and patients with COPD for structural epitopes unaffected by the proteolysis. These findings are similar to those observed previously with Der p1 and indicate a varying, and possibly specific, profile of epitopic dominance in the IgG response to antigens naturally presented at the mucosal level in patients with lung carcinoma, a model of mucosal cancer.
Michils
A
A
Chest Department, Erasme Hospital, University of Brussels, Belgium.
Casimir
G
G
Yernault
J C
JC
Gossart
B
B
Duchateau
J
J
D000328:Adult; D000818:Animals; D002417:Cattle; D005260:Female; D006801:Humans; D016056:Immunodominant Epitopes; D007074:Immunoglobulin G / Q000097:blood*; D007782:Lactoglobulins / Q000276:immunology*; D008173:Lung Diseases, Obstructive / Q000276:immunology; D008175:Lung Neoplasms / Q000276:immunology*; D008297:Male; D008875:Middle Aged
D016056:Immunodominant Epitopes; D007074:Immunoglobulin G; D007782:Lactoglobulins