"Aberrant" MHC class II expression in epithelia

HLA-D Antigen Expression and Langerhans' Cell Infiltrates in Thyroid Tumors

Papillary carcinomas (PCs) of thyroid are among the most common but least aggressive human malignancies. The factors explaining the indolence of these tumors are unknown but host-tumor immune interactions may play a role. This study was designed to determine if there is morphologic evidence of these. Frozen tissues collected from 21 PCs, 4 follicular adenomas (FAs), 4 follicular carcinomas (FCs), and 11 nodular hyperplasias (NHs) were stained immunohistochemically for HlLA-D antigens, lymphocyte, and macrophage markers; results were graded numerically. Paraffin-embedded tumors (35 PCs, 10 FAs, and 10 FCs) were stained for 5-100 protein to detect Langerhans' cells (LCs). Diffuse staining for HLA-D antigens and heavy mononuclear infiltrates were found more commonly in PCs compared to follicular neoplasms (FNs) or NHs. No consistent relationship was found between lymphocyte/macrophage infiltrates and expression of HLA-D antigens. The largest number of LCs was in PCs (median 11.8 cells/standard microscopic field [c/smf]), fewer cells were found in FA (3.7 c/smf), and the least in FC (0.05 c/smf). Features of host-tumor interaction including HLA-D expression and infiltrates with lymphocyte macrophages and LC are more strongly expressed in PC than other tumors. This may play a role in explaining their biological behavior.

HLA expression in hepatocellular carcinoma cell lines

The present study undertook to investigate the biological significance of human leucocyte antigen expression in hepatocellular carcinoma and to elucidate the role of potential modulating agents on human leucocyte antigen expression. These studies used several hepatic tumour-derived cell lines as in vitro model systems. The cell lines included PLC/PRF/5 (Alexander cell line), Hep3B, HepG2, TONG PHC, HA22T/VGH, HA59T/VGH and Mahlavu. The cell lines K562 and Raji were used as negative and positive controls, respectively. K562, a B lymphoid-derived cell line, was shown to express negligible amounts of human leucocyte antigens, while Raji, an erythromyeloid-derived cell line, expressed both class I and class II human leucocyte antigens as well as their respective invariant chains, beta 2-microglobulin and Ii. Using an ELISA, experiments performed on these cell lines confirmed the natural expression of class I and class II antigens by the HA22T/VGH and HA59T/VGH cell lines, whereas PLC/PRF/5 displayed class II surface antigens only. The effects of modulating agents such as interferon-gamma sodium butyrate and clofazimine on human leucocyte antigen expression were investigated using the HA22T/VGH, HA59T/VGH and TONG PHC cell lines. These agents increased class II and class II human leucocyte antigen expression on HA22T/VGH and TONG PHC cells, but had no effect on the HA59T/VGH cell line. The results suggest a potential use for these agents as modulators of human leucocyte antigen expression by human heptocellular cell lines.

HLA class II antigen expression and the autoimmune thyroid response in patients with benign and malignant thyroid tumors

To further understand the relationship between the immune system and the neoplastic human thyroid cell we investigated the degree of intrathyroidal lymphocytic infiltration and thyroid HLA class II expression in 17 patients with thyroid tumors. In another 60 thyroid tumor patients the association of thyroidal lymphocytic infiltration with thyroid autoantibody production was analyzed. In total 117 thyroid tissues were examined including tissue obtained at autopsy (n = 28), fetal thyroid tissue (n = 4), thyroid samples obtained from areas distant from benign follicular adenomas (n = 5), and 80 abnormal thyroids including patients with benign (n = 53) or malignant (n = 24) thyroid tumors and Hashimoto's thyroiditis (n = 3). Normal adult and fetal thyroid tissue had no significant lymphocytic infiltration and no detectable HLA-DR, -DP, or -DQ antigens on their thyroid follicular epithelial cells. The degree of lymphocytic infiltration in the nonneoplastic thyroid tissue of thyroid glands with benign and malignant thyroid tumors varied considerably and correlated with the presence and titer of serum thyroid autoantibodies measured by sensitive ELISA techniques. However, all but one of the benign follicular adenomas had thyroid cells negative for HLA class II determinants despite the presence of infiltrating lymphocytes, while 7 of 10 thyroid carcinomas expressed class II antigen (principally HLA-DR) even when only minor degrees of lymphocytic infiltration were present. These data indicate a correlation between lymphocytic infiltrates and serum thyroid autoantibody titers but the relationship with HLA class II expression is more complex. Since we have previously shown that HLA class II antigen expression can be induced by local interferon-gamma secretion, presumably from activated T cells, we conclude that estimates of simple thyroid lymphocytic infiltration and serum autoantibody secretion do not correlate with the degree of intrathyroidal T-cell activation. Furthermore, our observation of increased expression of HLA class II antigens in thyroid cancer suggests considerable cellular heterogeneity in susceptibility to HLA class II antigen induction in human thyroid disease.

HLA expression in human hepatocellular carcinoma

This study examines the expression of MHC class I and II antigens and their related invariant chains in 70 cases of human hepatocellular carcinoma (HCC), using monoclonal (Mabs) and polyclonal antibodies. In comparison with normal hepatocytes, the majority (94.3%) of HCCs show enhancement or acquisition of HLA-A, B, C in either a cytoplasmic or membranous distribution, with staining being uniformly distributed throughout the specimen. HLA-A, B, C was accompanied by beta 2-microglobulin expression in all but two cases. Although 44.9% of specimens showed HLA-DR expression, positively staining tumour cells were often sparse and heterogeneously distributed. By contrast, the invariant (I) chain, present in 47.1% of cases, was frequently intensively stained and extensive in distribution. HLA-DR staining was usually cytoplasmic although two cases showed faint membranous enhancement. In addition to HLA-DR and I-chain, two cases also showed HLA-DQ staining. Display of MHC antigens was not related to tumour differentiation or size of the lesion (resected vs. advanced tumours). It is possible that the acquisition of class I antigens by the majority of HCCs may influence tumour behaviour.

HLA expression in human hepatocellular carcinoma

This study examines the expression of MHC class I and II antigens and their related invariant chains in 70 cases of human hepatocellular carcinoma (HCC), using monoclonal (Mabs) and polyclonal antibodies. In comparison with normal hepatocytes, the majority (94.3%) of HCCs show enhancement or acquisition of HLA-A, B, C in either a cytoplasmic or membranous distribution, with staining being uniformly distributed throughout the specimen. HLA-A, B, C was accompanied by beta 2-microglobulin expression in all but two cases. Although 44.9% of specimens showed HLA-DR expression, positively staining tumour cells were often sparse and heterogeneously distributed. By contrast, the invariant (I) chain, present in 47.1% of cases, was frequently intensively stained and extensive in distribution. HLA-DR staining was usually cytoplasmic although two cases showed faint membranous enhancement. In addition to HLA-DR and I-chain, two cases also showed HLA-DQ staining. Display of MHC antigens was not related to tumour differentiation or size of the lesion (resected vs. advanced tumours). It is possible that the acquisition of class I antigens by the majority of HCCs may influence tumour behaviour.

The relationship between epithelial Ia expression and the inflammatory cell infiltrate during experimental oral carcinogenesis

The development of oral epithelial expression of Ia antigens and its relationship to the presence of IL-2r+ (CD25+) cells was investigated in rats treated with the water soluble carcinogen 4-nitroquinoline-N-oxide (4NQO). Acetone fixed frozen sections of the palate and tongue were stained using an indirect immunoperoxidase technique and monoclonal antibodies to rat Ia (I-A & I-E) and IL-2 receptor. After 4 weeks 4NQO treatment all rats expressed oral epithelial Ia but thereafter (2-9 months) expression was present in only 20-40% of animals. Epithelial expression of Ia by histologically normal, dysplastic and neoplastic epithelium was always associated with the presence of an underlying inflammatory cell infiltrate containing CD25+ cells. Overall there were significantly more CD25+ cells in tissue specimens containing Ia+ epithelium compared with Ia- epithelium. Furthermore, during the first 4 weeks of carcinogen treatment, a significant positive correlation was found between the CD25+ cell density and occurrence of focal epithelial Ia expression. These results, together with analysis of the T cell, NK cell, macrophage and B cell content of the infiltrates induced by 4NQO, suggest that the CD25+ cells represent activated T cells. Thus, our results in this experimental model are consistent with the idea that epithelial expression of Ia is the result of production of IFN-gamma by locally activated T cells.