Genetic variants of immunoglobulin γ and κ chains influence humoral immunity to the cancer‐testis antigen XAGE‐1b (GAGED2a) in patients with non‐small cell lung cancer
GM (γ marker) allotypes, genetic variants of immunoglobulin γ chains, have been reported to be associated strongly with susceptibility to lung cancer, but the mechanism(s) underlying this association is not known. One mechanism could involve their contribution to humoral immunity to lung tumour‐associated antigens. In this study, we aimed to determine whether particular GM and KM (κ marker) allotypes were associated with antibody responsiveness to XAGE‐1b, a highly immunogenic lung tumour‐associated cancer‐testis antigen. Sera from 89 patients with non‐small cell lung cancer (NSCLC) were allotyped for eight GM and two KM determinants and characterized for antibodies to a synthetic XAGE‐1b protein. The distribution of various GM phenotypes was significantly different between XAGE‐1b antibody‐positive and ‐negative patients (P = 0·023), as well as in the subgroup of XAGE‐1b antigen‐positive advanced NSCLC (P = 0·007). None of the patients with the GM 1,17 21 phenotype was positive for the XAGE‐1b antibody. In patients with antigen‐positive advanced disease, the prevalence of GM 1,2,17 21 was significantly higher in the antibody‐positive group than in those who lacked the XAGE‐1b antibody (P = 0·026). This phenotype also interacted with a particular KM phenotype: subjects with GM 1,2,17 21 and KM 3,3 phenotypes were almost four times (odds ratio = 3·8) as likely to be positive for the XAGE‐1b antibody as the subjects who lacked these phenotypes. This is the first report presenting evidence for the involvement of immunoglobulin allotypes in immunity to a cancer‐testis antigen, which has important implications for XAGE‐1b‐based immunotherapeutic interventions in lung adenocarcinoma.