Expression of beta 2-microglobulin by human benign and malignant mesenchymal and neurogenic tumours

Human myosarcomas, liposarcomas, meningosarcomas, glioblastomas and malignant schwannomas, their benign counterparts and normal cells from which these tumours derive, were examined for the expression of beta 2-microglobulin (beta 2m). Formalin fixed specimens from these tumours were studied by light microscopy employing the immunoperoxidase method with the use of antibodies directed towards beta 2m. The malignant tumours showed a broad spectrum from unstained to strongly stained tumours, most pronounced among myosarcomas. In addition, most stained tumours displayed a mosaic staining pattern in that unstained areas alternated with stained. There was a tendency towards increased staining for beta 2m in malignant compared to normal cells; this was also observed in the benign tumours although to a lesser degree. The results differ from most earlier studies, mainly of carcinomas which have shown a tendency towards down-regulation of MHC I molecules on the tumour cells. The results are discussed in relation to concepts of immune surveillance of tumours.