Figure 4.

(A, B) Primary tumor stained by immunohistochemistry method showing remarkable heterogeneity of B2M and HLA-A expression. (A) Representative breast cancer case with heterogeneous expression of HLA-A and B2M. Strongly B2M positive (orange box) and B2M negative (green box) tumor areas adjacent to each other. Similarly, areas of strong HLA-A positivity and negativity were seen (orange and green box respectively). (B) Representative case of colorectal cancer displaying heterogeneous B2M expression with tumor areas showing strong membrane expression of B2M (orange box) adjacent to virtually negative areas (green box). HLA-A expression in the specimen was consistently positive on tumor cell membrane as well as cytoplasm (orange box and green box).