SUMMARYHLA class I antigens are composed of a major histocompatibility complex (MHC) encoded heavy chain that is associated non‐covalently with a light chain β‐2 microglobulin (β‐2m). When the HLA complex is metabolized, β‐2m is shed into the serum. A large variety of human and experimental tumours have altered MHC class I expression. In a previous study we observed elevated mean β‐2m serum levels in breast cancer patients, as compared to controls. To study the relationship between tumour expression and serum levels, we examined 54 patients with breast cancer. Tumour β‐2m was determined by immunohistochemistry and serum levels by the ELISA technique. Of the 54 patients, 38 had low and 16 had high β‐2m expression on the tumour. There was a significant correlation between tumour β‐2m and serum β‐2m levels (P= 0.02), with patients whose tumours expressed high β‐2m having high serum β‐2m levels. There was an inverse correlation between tumour grade and tumour β‐2m expression which approached statistical significance (P= 0.06). These findings suggest that in a substantial number of patients the high serum levels derive from shedding of β‐2m from tumour cells. These levels may have implications for tumour growth and metastases due to
展开▼
