Down-regulated expression of human leukocyte antigen class I heavy chains is linked to poor prognosis in non-small cell lung cancer

32 The aim of this study was to clarify the associations between expression of human leukocyte 33 antigen (HLA) class I on non-small-cell lung cancer (NSCLC) cells, and patient survival. To 34 address this, immunohistochemical staining for HLA class I was performed on specimens 35 from 111 patients with NSCLC, and overall survival curves were compared using the log36 rank test. In addition, multivariate analyses were undertaken using Cox’s proportional hazard 37 model. The cases were divided into five classes based on expression of HLA class I heavy 38 chain and 2-microglobulin. Overall survival for patients with tumors lacking HLA class I 39 heavy chain (30 cases; 27.0%) was significantly compromised. Multivariate analysis revealed 40 the absence of HLA class I heavy chain to be an independent predictor of poor prognosis. 41 There was a trend towards unfavorable prognosis for those patients whose tumors did not 42 express 2-microglobulin (57 cases; 51.4%). Down-regulation of HLA class I heavy chain 43 expression significantly correlated with down-regulation of 2-microglobulin expression ( ; 44 p<0.01). Cases lacking both HLA class I heavy chain and 2-microglobulin expression (23 45 cases; 20.7%) had a statistically significant unfavorable prognosis compared with other cases 46 (p<0.05). Our data demonstrate that lack of HLA class I heavy chain expression in tumor 47 cells is an independent poor prognostic factor for NSCLC survival, and is likely to have an 48 important influence on immune surveillance in patients. 49