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The ultrastructural expression of laminin and fibronectin was studied in human colonic mucosa with a pre-embedding immunoperoxidase technique. Both antigens were present in epithelial basement membrane. The lamina densa was uniformly and homogeneously immunostained by both fibronectin and laminin, while the lamina rara showed discrete, positive sites occasionally connecting the lamina densa with the epithelial plasma membrane. In the lamina reticularis, fibronectin was diffusely positive, while laminin showed a discontinuous positivity only in the uppermost region in vicinity of the lamina densa. Collagen fibrils were regularly decorated by fibronectin-positive material. Basement membranes in the capillary wall showed a similar pattern of reactivity both with laminin and fibronectin. These results point out that laminin as well as fibronectin are integral components of intestinal mucosa basement membranes.

A 16-yr-old white female was affected by continuous fever, pancytopenia with relative increase of T-8 lymphocytes, severe bone marrow hypoplasia, generalized lymphadenomegaly and splenomegaly. A first lymph node biopsy, obtained at the onset of the disease, was involved by a paracortical tumor with some S-100+ "lymphocyte-like" cells in the neoplastic areas; in the cell suspension, 70-80% of cells were E4+/E37+ lymphocytes with prevalent expression of the T-8 phenotype (52%). A second lymph node biopsy, obtained five months later, was involved by a diffuse proliferation of S-100+ cells with high mitotic activity; in the cell suspension, the majority of cells were E-/T-11+/T-3+/T-8+. At the TEM level, the neoplastic cells were characterized by regular or indented nuclei with finely dispersed chromatin and by regular or indented nuclei with finely dispersed chromatin and by irregular cytoplasmic profiles with thick pseudopodia-like projections. The possibility is discussed that this neoplasm may share some similarities with the T-gamma lymphoma being part of a poorly described group of tumors with intermediate features between T cell lymphoma and malignant histiocytosis.

The subcellular localization of sulphated glycoconjugates was determined at the ultrastructural level by using the high iron diamine (HID) technique for sulphate groups in the absorptive cells of human colonic mucosa. Stained material was observed on the apical plasma membrane, in intracytoplasmic vesicles and in the Golgi complex. In this organelle, the last two or three cisternae of the trans side and the trans-Golgi network (TGN) were labelled, as well as a variable number of coated and noncoated vesicles facing the trans side and surrounding trans-Golgi network. These findings point to the trans side of the Golgi apparatus and trans-Golgi network as the subcompartments functionally involved in the sulphation of glycoconjugates.

Ten cases of non-Hodgkin's lymphomas, mainly composed of large multilobated cells, have been studied. Our results are consistent with the view that they represent a somewhat heterogeneous group of lymphoid tumours displaying different morphological, clinical and immunophenotypic features. In B-cell type the large multilobated cells were histologically characterized by prominent nucleoli and distinctly basophilic cytoplasm whereas in the T-cell type they had indistinct or small nucleoli and ill-defined weakly eosinophilic cytoplasm. These differential features between B- and T-cell type were confirmed by electron microscopy. From a clinical standpoint B-cell type was characterized by a constant involvement of lymphoid tissues (lymph nodes and/or Waldeyer's ring); T-cell type showed, on the contrary, a more frequent involvement of extra-lymphoid sites (mainly bone and subcutaneous tissues). Our study provides some morphological features that may be helpful for a correct differential diagnosis in this heterogeneous group of non-Hodgkin's lymphomas.

S-100 protein is an immunohistochemical marker for a subset of dendritic cells, the interdigitating reticulum cells (IDRCs), which are mainly located in T-dependent areas of lymphoid tissues. In the present study we have investigated the distribution of S-100-positive cells in lymph nodes, spleen, thymus and peripheral blood of normal subjects. Immunoreactivity for S-100 protein was demonstrated in large cells with dendritic morphology and in small lymphocyte-like cells present in the lymph node paracortex, thymic medulla, splenic periarterial lymphatic sheaths (PALS) and in peripheral blood. S-100-positive lymphocyte-like cells were frequently detected around high endothelial venules (HEV) and were present in numbers comparable to those of S-100-positive IDRCs. Immunoelectron microscopy confirmed the existence of positive cells with lymphoid morphology and revealed that the intracellular distribution of the immunoreaction product was similar in lymphoid and dendritic cells. Further characterization of S-100-positive cells demonstrated that both lymphoid and dendritic cells were unreactive with a large panel of monocytic and macrophage markers.

In the present study we have evaluated the histological, immunohistochemical, ultrastructural and cell surface phenotypic features of lymph nodes from 19 intravenous drug abusers and two homosexual men with persistent lymphadenopathy syndrome and from six control patients. Our investigation has demonstrated that the lymphadenopathy of drug abusers is characterized by: (a) specific histological features with evidence of evolution from an initial hyperplastic-reactive to a late regressive-destructive stage; (b) T-cell surface phenotype distribution similar to that in the peripheral blood of homosexuals; (c) peculiar infiltration of the germinal centres by T8+ cells and by S-100+, T6+ interdigitating reticulum-like cells; (d) electron microscopic features indicating the presence of virus bodies in lymph node cells and in the intercellular spaces. These data suggest that the lymphadenopathy of drug abusers and homosexuals are similar pathological conditions with characteristic features which allow histological differentiation of this entity from those found in other viral infections.

We have undertaken a study on 200 autopsy lung samples collected from subjects who lived in the Rome urban area and were not occupationally exposed to mineral dusts. The samples belonged to subjects who died aged between 15 and 65, both male and female. Subjects suffering from diseases and drug addicts were excluded. The purpose of this investigation was to determine whether any correlation existed between subjects' life-style, in particular smoking habits, and the presence of mineral fibres and dusts in their lungs. The data obtained were compared with those on airborne mineral dusts in the environment of the subjects themselves, particularly data on the concentration and types of mineral fibres present in that environment.

The effect of adding cetylpyridinium chloride to the fixative on the preservation of sulphated glycosaminoglycans (SGs) was studied in human normal colonic mucosa. SGs were visualized at the ultrastructural level through the application of Spicer's High Iron Diamine (HID) technique followed by a post-fixation with potassium ferrocyanide-reduced osmium tetroxide. SGs were mainly localized in basement membranes of epithelium and capillary wall and along collagen fibers. The morphology of the reactive sites depended on the presence of cetylpyridinium chloride, SGs being granular in absence of the salt and more or less elongated when cetylpyridinium chloride was added to the fixative. We suggest that the use of cetylpyridinium chloride during fixation may help to preserve SG molecule at the ultrastructural level.