殺手細胞免疫球蛋白樣受體(Killer-cell immunoglobulin-like receptor，KIR)是自然殺手細胞(NK細胞)表面的一組受體，其可傳遞訊息引起NK細胞的活化和抑制作用。KIR基因座位於人類基因體最具變異性的區域之一，為探討大腸直腸癌相關的KIR基因型，本研究以序列特異性引子聚合酶鏈鎖反應鑑定119名大腸直腸癌患者的KIR基因型，並將之與慈濟骨髓庫97名捐贈者的KIR基因型進行統計分析，結果顯示：大腸直腸癌組別之KIR2DL5B和KIR3DL1基因攜帶頻率顯著低於慈濟對照組(KIR2DL5B: 6.7% vs. 16.5%, P= 0.023; KIR3DL1: 95.8% vs. 100%, P= 0.041)，同時，其帶有全長型KIR2DS4基因(KIR2DS4fl)的比例也有較低的趨勢(78.1% vs. 87.6%, P=0.069)；另一方面，大腸直腸癌組別出現23種KIR基因型，而慈濟組別則有27種KIR基因型，二者合計共有40種KIR基因型。針對染色體單倍型分析，兩組之A單倍型與B單倍型的比例都接近3：1，而二者之A/A同型合子的比例也都接近53%。然而屬於B/X單倍型之大腸直腸癌患者攜帶KIR2DS4fl基因的頻率顯著低於慈濟組(69.1% vs. 87.0%, P=0.033)；此外，B/X單倍型患者的整體存活相較於A/A單倍型患者有較優的趨勢，二者之中位整體存活時間分別為大於70個月和34個月(P=0.083)。總結而論，KIR基因型除了影響NK細胞之發育與活化，並兼具調控腫瘤微環境免疫反應的角色，進而可能做為大腸直腸癌之預後因子。

Killer-cell immunoglobulin-like receptors (KIRs) can regulate the activation and inhibition of nature killer (NK) cells by signal transduction. KIR genes are clustered in one of the most variable regions of human genome. To study colorectal cancer (CRC)-associated KIR genetic profiles, 119 patients were recruited and their KIR genotypes were determined by using polymerase chain reaction with sequence-specific primers. The KIR gene frequencies and genotypes of patients (CRC group) were compared with 97 Han Taiwanese from the Buddhist Tzu Chi Taiwan Marrow Donor Registry (Tzu Chi group). The gene frequencies of KIR2DL5B and KIR3DL1 in CRC group were significantly lower than that in Tzu Chi group (6.7% vs. 16.5%, P=0.023; 95.8% vs. 100%, P=0.041, respectively). Meanwhile, a lower frequency of full-length KIR2DS4 gene (KIR2DS4fl) was observed in CRC group, although not statistically significant (78.1% vs. 87.6%, P=0.069). There were 23 KIR genotypes identified in CRC group, 27 genotypes in Tzu Chi group, and 40 genotypes in total. On the other hand, CRC and Tzu Chi groups showed a similar 3:1 ratio of haplotypes A and B. Meanwhile, the frequencies of haplotype A/A in CRC and Tzu Chi groups were 53.8% and 52.6%, respectively. Whereas, a significantly lower frequency of KIR2DS4fl was observed in CRC patients with haplotype B/X compared with Tzu Chi group (69.1% vs. 87.0%, P=0.033). In addition, CRC patients with haplotype B/X showed better overall survive (OS) compared with those with haplotype A/A. The median OS surpassed 70 months in the haplotype B/X subgroup, while 34 months in the haplotype A/A subgroup (P=0.083). Taken together, KIRs modulate the immune surveillance in tumor microenvironment through regulation of NK cell development and activation. Accordingly, diverse KIR genetic profiles might serve as a prognostic factor in CRC.