Differential expression of immunoglobulin kappa chain constant region in human abdominal aortic aneurysm

A number of the research into the pathogenesis of the abdominal aortic aneurysm (AAA) have focused on the alteration of gene expression. The current technique for elucidating alterations of gene expression has a setback in that many artifact complementary DNA (cDNA) products present abnormal polymerase chain reaction (PCR) amplification. Our study was designed to identify differentially expressed genes in AAA using the annealing control primer (ACP) system, which was recently developed to identify only authentic genes.

The tissues of the human abdominal aorta were obtained from the patients of AAA and aortic occlusive disease (AOD), and normal abdominal aorta (NA) from brain death donors. Total RNAs were isolated from three groups of human abdominal aorta (10 AAA, five NA, three AOD) and then reverse transcribed into complementary DNA (cDNA). The ACP method was done to screen the difference in the expression pattern of the mRNA (mRNA).

One differentially expressed cDNA band was detected in AAA but not in NA and AOD. This cDNA was sequenced and computer searching against the GenBank revealed that the cDNA had more than 90% identity with the immunoglobulin kappa chain constant region (Ig kappa-C).

Our finding suggests that differentially expressed Ig kappa-C gene only in AAA is a candidate gene that may play a pivotal role in the pathogenesis of AAA formation. The correlation of mRNA level and protein level is, however, not clear. Thus, to directly identify the role of Ig light chains in the pathogenic event of AAA, the further study comparing the level and kinds of expressed protein with the corresponding Ig kappa-C gene will be required.