Total Loss of MHC Class I is an Independent Indicator of Good Prognosis in Breast Cancer

Tumours may either fail to stimulate an immune response a process known as immune ignorance or they may elicit innate and/or adaptive immunity in a process known as immune editing. major histocompatibility complex (mhc) may play a pivotal role in immune editing as they present peptides that are recognised by cytolytic t cells. in contrast if mhc antigens are down regulated to avoid t cell attack they become susceptible to nk killing. in this study a large set of samples from patients with primary operable invasive breast cancer was evaluated for the expression of mhc class i heavy and light by immunohistochemical staining of 439 breast carcinomas in a tissue microarray. forty seven percent (206 / 439) of breast carcinomas were considered negative for hla class i heavy chain, whereas lack of anti-(32 m-antibody staining was observed in 39% (167/424) of tumours, with only 3% of the p2 m -negative tumours expressing detectable hla heavy chain. a correlation with patient outcome showed a direct relationship between patient survival and hla-negative phenotype (log rank= 0.004). a positive relationship was found between the intensity of expression of mhc class i light and heavy chains expression and histological grade of invasive tumour (p< 0.001) and nottingham prognostic index (po.001). to investigate whether hla expression had independent prognostic significance, cox multivariate regression analysis, including the parameters of tumour size, lymph node stage, grade and intensity of hc10 and anti-02 m staining, was performed. in this analysis, lymph node stage (p< 0.001), tumour grade (p= 0.005) and intensity of mhc class i light and heavy chains expression were shown to be independent prognostic factors predictive of overall survival (p-values for hc10 = 0.047 and (32m = 0.018).