An immunocytochemical and ultrastructural study using the Fab fragment of an anti-human Ig antibody labelled with peroxidase was carried out on affected lymph nodes from five Hodgkin's disease patients. The tumor cells (Reed-Sternberg cells and Hodgkin cells) showed an exclusively hyaloplasmic granular staining. By comparing these grains with ribisome staining. By comparing these grains with ribosome staining of the endoplasmic reticulum of plasma cells it could be suggested that they are free risobomes. This ribosomal Ig synthesis is a major argument for the B lymphocyte nature of Reed-Sternberg and Hodgkin cells. The total absence of vacuole staining allows us to conclude that these cells are not histiocytic or macrophage derivatives.

This work is devoted to the analysis of the nature of lymphoblastic lymphoma/leukemia with convoluted nuclei which were initially described by Barcos and Lukes. Ultrastructural, cytochemical, and immunologic features of tumor cells were investigated in patients chosen according to known morphologic criteria. Through results of the E rosette test, the patients were divided into two groups (E+ and E-). In the E+ group, the predominant features were sex (only men), the mediastinal localization, and the focal positivity of the acid phosphatase reaction. Cytotoxicity tests with rabbit antihuman T-lymphocyte anti-serum confirmed the results of the E rosette test in the 3 patients of the E+ group who were tested and were also positive in 2 patients from the E- group (1 of these 2 patients had the characteristics found in the E+ group and can thus be related to this group; the other patient had none of these characteristics). This raises the question of a leukemia arising from a less differentiated T-cell but this interpretation is limited by the specificity of the anti-T-serum. Ultrastructural study defines more precisely the convoluted aspect but does not at present allow a distinction between the two groups.