NATURAL-HISTORY OF HLA EXPRESSION DURING TUMOR-DEVELOPMENT

HLA expression is frequently altered in tumours compared to the tissue from which they originate. Given the central role of MHC products in the restriction of T-cell recognition, regulation of tumour HLA expres sion might be a strategy for the evasion of immune surveillance by the malignant cells. Federico Garrido, Peter Stern and colleagues present data from a variety of tumour types, suggesting that HLA class I alte rations may occur at a particular step between the development of an i n situ lesion and an invasive carcinoma.