HLA class I and II expression was studied on 244 (177 primary and 67 metastatic) solid human tumours of different origin. Alkaline immunophosphatase (APAAP) and immunoperoxidase were used on cryostatic sections to
stain MHC
antigens. Monomorphic MoAbs were used against class I heavy chain,
beta 2-microglobulin, DR, DQ and DP molecules. Class I expression was homogeneous on colon,
melanoma and epidermoidal primitive tumours. Loss of HLA
class I antigens was more frequent on
basal cell carcinomas and
sarcomas and was related to tumour differentiation on larynx
carcinoma. Class I expression was heterogeneous on breast, larynx and stomach primitive
neoplasias. Class I negative tumours were more frequent on metastatic than on primitive
melanomas. Divergence of class I between primary tumours and autologous
metastases was observed on
melanomas, larynx and
colorectal carcinomas. Class II expression was heterogeneous on all tumours and in a large number of cases was associated with high intensity of leukocytic infiltrate.
HLA-DR expression was higher than
HLA-DP and
HLA-DQ (DR greater than DP greater than DQ) and was related to tumour progression. Four human tumour cell lines were modulated with recombinant
interferon-gamma for HLA class I and II
antigens. Different HLA profiles were obtained: increased class I and II expression, increased class II or a low response. Finally, class I genes from 22 tumours were compared with autologous normal cells by Southern blot analysis: 12 tumours were class I positive and 10 negative. No clear differences in RFLP were observed that could be associated with class I rearrangement. The results are discussed in relation to the role that
histocompatibility antigens may play in tumour progression and invasiveness.