Immunophenotype analysis of dendritic cells and lymphocytes associated with cutaneous malignant melanomas.

The purpose of this study was to investigate the relationship between changes in density and distribution of dendritic cells, both in epidermis and in peritumoral infiltrate, and lymphocyte subset variations in malignant melanomas (MM) of patients belonging to different risk groups. The collective immunoreactive expression of six markers (S100 protein, CD1-a, HLA-DR, CD4, CD8 and CD25) was analyzed in 13 cutaneous malignant melanomas. Changes were observed in density and distribution of Langerhans cells (LC) (S100+, CD1-a+) in the epidermis overlying the tumor, as well as in peritumoral and intratumoral locations, independently of the tumor-invasion level. A decrease was recorded in LC (S100+, CD1-a+) in the epidermis overlying six tumors, whereas most of the MM studied showed an increase of LC (S100+, CD1-a+) in peritumoral infiltrate. The expression of HLA-DR in tumor cells was controversial; it was observed in three moderate-risk MM, but it was negative in high-risk tumors. The percentage of CD4+ cells was in most cases greater than that of CD8+ in the peritumoral infiltrate, irrespective of the degree of histopathological malignancy. The concomitant expression of the lymphocytic activation marker CD25 (receptor for interleukin 2) in lymphocytic infiltrate was variable. Peritumoral infiltrate in three high risk MM contained few CD25+ cells, and a concomitant decrease was recorded in LC. This preliminary report shows that alterations in the density and distribution of LC may be responsible for determining the degree or T lymphocyte activation, and this may be critical for the development of effective tumor-directed immunity. Further studies are required to demonstrate these hypothetical interrelations.

HLA molecule expression in cutaneous squamous cell carcinomas: an immunopathological study and clinical-immunohistopathological correlations.

A correlation between the lack of MHC class I gene expression on murine tumor cells and their ability to grow and metastasize has recently been established. This paper studies HLA-ABC and HLA-DR antigen expression in tumor cells and mononuclear infiltrate of 26 cutaneous squamous cell carcinomas (SCC). Our results showed a heterogeneous expression of HLA class I molecules in these tumors. No significant correlation between the degree of HLA class I molecule expression and anatomical-clinical parameters was found. Class II antigen expression was correlated to the histopathological type and to the degree of cell differentiation. Most mononuclear cells infiltrating the tumor were T-lymphocytes. No correlation with anatomical-clinical parameters was found.

HLA expression in basal cell carcinomas.

Decreased expression of MHC class I molecules in tumor cells has been reported to be associated with enhanced malignancy both in human and murine tumors. This paper studies HLA-ABC and HLA-DR expression in 56 basal cell carcinomas. Our results show that these tumors have a heterogeneous expression of MHC class I molecules: 11% exhibit uniform staining of most tumor cells; 25% are only partially positive, and the remaining 64% are MHC class I negative. A positive correlation between the level of HLA-ABC molecule expression and the degree of histological differentiation has been found. The expression pattern of tumor cells with anti-class II monoclonal antibodies shows weak homogeneous staining in 5%, staining in only a few areas of the tumor in 32%, whereas 63% has no significant staining for MHC class II antigens. Most mononuclear cells infiltrating the tumor were T lymphocytes (CD-3 positive). Results also show that 68% of the tumors express class II molecules homogeneously in the infiltrate. The expression of class II antigens in infiltrating lymphocytes correlated with the level of class II expression in the tumor cells probably as a consequence of lymphokine production by activated T cells.