Italo Caorsi

A second look at the ultrastructure of the Langerhans cell of the human epidermis

The ultrastructure of the Langerhans cells of the normal human epidermis was investigated by applying conventional techniques and four standardized zinc iodide—osmium (ZIO) procedures. One of these methods stained the Langerhans cell granule (LCG) selectively. This made it possible to study semithick sections (0.5 to 1 μ m) under the electron microscope, which, in turn, allowed a better understanding of the internal structure of the LCG. This procedure together with a microdensitometric analysis led to the development of a tridimensional model of the LCG. Two components were easily distinguished in the LCG, one disk shaped (LCD) and one a vacuole (LCV). A second ZIO procedure stained tubular formations which were seen to be connected to the LCD. This method also stained the content of the LCV and the vesicles of the Golgi complexes. A third ZIO procedure stained, in addition, the cisternae of the Golgi complexes. The histochemical and microdensitometric analysis of the membrane limiting the LCG revealed that this is a unique type of membrane within the Langerhans cell. The application of the four ZIO procedures to material processed for light microscopy demonstrated histochemical differences between Langerhans cells, melanocytes, and melanin granules of the keratinocytes. The selective staining of the Langerhans cells by one of the ZIO methods was useful to establish the gross morphology of these cells as well as their relationships with the other cell types of the epidermis. The general arrangement of the Langerhans cells suggests that they are functionally polarized and closely related to events taking place in the free surface of the epidermis.

Anticardiolipin Antibodies in Acute Poststreptococcal Glomerulonephritis and Streptococcal Impetigo

Anticardiolipin (aCL) antibodies have been described in diverse clinical situations, linked to the risk of thrombosis in different vascular locations. They have been rarely studied in renal diseases, and occasionally they have been associated with glomerular thrombosis. We analyzed the incidence of aCL (isotypes IgG, IgA, and IgM) in samples, taken during the acute phase of the disease, from 27 well-documented patients having acute poststreptococcal glomerulonephritis. Twelve cases were positive on IgG testing, 1 case on IgA testing only, and no one was positive on IgM testing. A serological follow-up was performed with a second sample taken about 7 months later, for the patients initially positive on IgG testing showing persistence in 9. Clinical variables during the acute phase and after a follow-up period of 25 (range 6–89) months were analyzed for possible associations with the presence of these antibodies, but non was significantly related. Renal histopathological investigation did not reveal particular findings in the aCL-positive patients, and glomerular thrombosis was not found in any case. In addition, serum samples from 12 streptococcal impetigo patients without renal involvement were analyzed, showing similar incidence (4 positive on IgG testing, 1 of them positive on IgM testing as well, and no one positive on IgA testing) and titers of aCL antibodies. We conclude that the presence of aCL antibodies in acute poststreptococcal glomerulonephritis may be a marginal immunological phenomenon unrelated to the glomerular disease, triggered by the streptococcal infection.

Langerhans Cells in Squamous Exocervical Carcinoma: A Quantitative and Ultrastructural Study

The gross morphology, density, distribution, and ultrastructure of the Langerhans cell (LC) in the human exocervix in cases of cervical intraepithelial neoplasia (CIN) and incipient carcinoma were investigated. Two zinc-iodide-osmium (ZIO) procedures were applied to epithelial sheets and to tissue sections for light and electron microscopy. The ZIO methods as well as conventional electron microscopy revealed the presence of LCs in CIN, in the invasive prongs, and in the lymphoid infiltrate of the chorion. The epithelial sheets demonstrated a LC density 3.5 times higher than we have previously reported for the normal exocervix. The region around the external os displayed the highest LC density and the most advanced grades of CIN. The LCs were classified into six types according to the number of processes and secondary branches. The most ramified types were more abundant in the neoplastic exocervix than in the normal exocervix. The LC in all locations of the exocervix with carcinoma showed hypertrophy of the rough and smooth endoplasmic reticula and a large number of filaments. The RER displayed dilated cisternae containing electron-dense material. Specialized contacts between LCs and lymphocytes were an outstanding finding. These findings suggest that the LC might play an important role in the neoplastic process.

Cellular and subcellular distribution of 2,4-dinitrophenyl groups in mouse epidermis and regional lymph nodes after epicutaneous application of 2,4-dinitrofluorobenzene

SummaryThe cellular and subcellular distribution of 2,4-dinitrophenyl (DNP) groups in the epidermis and regional lymph nodes of the mouse was investigated after epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) to sensitized and non-sensitized mice. The peroxidase-antiperoxidase method and the immunogold technique were used to visualize the DNP groups at both light and electron microscopic levels. The highest intensity of immunolabelling was found on tonofilaments of keratinocytes present in the upper layers of the epidermis. On the other hand, in vitro experiments showed that DNFB has the capacity to bind keratin which, together with immunocytochemistry, suggests that this molecule may be one of the skin protein carriers for DNFB. In addition, intense immunostaining for DNP was observed in the Golgi area of some epidermal Langerhans cells. Cells immunoreactive to DNP were also observed in the marginal sinus of cervical lymph nodes 6, 12 and 24 h after challenge. Immunoelectron microscopy revealed immunoreactive DNP groups in phagosomes of Langerhans cells at this site. The present findings support the hypothesis that the hapten DNFB penetrates passively into the cytoplasm of Langerhans cells, concentrates in the Golgi area and, during the migration of Langerhans cells to the lymph nodes, it is probably processed in the lysosomes before its presentation to T lymphocytes.

Cytochemistry and Ultrastructure of Normal and Neoplastic Cells Exfoliated from the Human Uterine Cervix

Cells exfoliated from the uterine exocervix from normal women at different stages of the reproductive period and from patients with invasive carcinoma were studied. Cell pellets were fixed in aldehydes and two different concentrations of OsO4, and embedded in methacrylate or Epon. Semithick sections were used for general light microscopic study and for the visualization of glycogen. Ultrathin sections were used for conventional electron microscopy, high resolution analysis of the plasma membrane, and the demonstration of glycogen and cell surface glycoconjugates by the Thiery method. Semithick sections stained with the Thiery method and viewed under the electron microscope were used for the study of surface projections. Based on the size, shape, nuclear characteristics, amount and distribution of glycogen, type of surface protrusions, density and distribution of surface glycoconjugates, and plasma membrane fine structure, the cells exfoliated from all normal uterine cervices were grouped into five cell types. It is suggested that these types correspond to cells located in the different layers of the exocervical epithelium and, consequently, represent different degrees of normal differentiation. The plasma membrane of carcinoma cells shared most of the characteristic of that of the least differentiated normal cells, indicating an early deviation of the differentiation process in carcinoma cells.