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Overexpression of the p16 protein has been reported in breast cancer and may trigger the secretion of antibodies against itself. Circulating anti-p16 antibodies that were detected with a recombinant protein have been reported in breast cancer. The present study was designed to determine whether the levels of circulating IgG antibody to p16 protein-derived linear antigens are altered in breast cancer. An enzyme-linked immunosorbent assay (ELISA) was developed in-house to determine circulating IgG against peptide antigens derived from the p16 protein in 152 female breast cancer patients and 160 healthy female subjects. The Student's t-test revealed that breast cancer patients exhibited significantly higher levels of anti-p16 IgG antibody compared to control subjects (t=2.02, P=0.045). In addition, ductal cancer appeared to be the main type contributing to the increased levels of circulating anti-p16 antibodies (t=2.08, P=0.038). Of all four stages of breast cancer, stage I was associated with the highest levels of IgG antibody (t=2.02, P=0.045) and receiver operating characteristic (ROC) analysis demonstrated that the area under the ROC curve was 0.74 (95% confidence interval: 0.65-083) and that the sensitivity against a specificity of 90% was 30.3%. Therefore, the levels of circulating IgG antibody to the p16 protein may be a potential biomarker for early diagnosis of breast cancer. [ABSTRACT FROM AUTHOR]

In science, the guinea pig is known as one of the gold standards for modeling human disease. It is especially important as a molecular and cellular biology model for studying the human immune system, as its immunological genes are more similar to human genes than are those of mice. The utility of the guinea pig as a model organism can be further enhanced by further characterization of the genes encoding components of the immune system. Here, we report the genomic organization of the guinea pig immunoglobulin (Ig) heavy and light chain genes. The guinea pig IgH locus is located in genomic scaffolds 54 and 75, and spans approximately 6,480 kb. 507 VH segments (94 potentially functional genes and 413 pseudogenes), 41 DH segments, six JH segments, four constant region genes (m, c, e, and a), and one reverse d remnant fragment were identified within the two scaffolds. Many VH pseudogenes were found within the guinea pig, and likely constituted a potential donor pool for gene conversion during evolution. The Igk locus mapped to a 4,029 kb region of scaffold 37 and 24 is composed of 349 Vk (111 potentially functional genes and 238 pseudogenes), three Jk and one Ck genes. The Igγ locus spans 1,642 kb in scaffold 4 and consists of 142 Vl (58 potentially functional genes and 84 pseudogenes) and 11 Jl -Cl clusters. Phylogenetic analysis suggested the guinea pig's large germline VH gene segments appear to form limited gene families. Therefore, this species may generate antibody diversity via a gene conversion-like mechanism associated with its pseudogene reserves. [ABSTRACT FROM AUTHOR]