Studies by electron microscopy of epidermis after topical application of mercuric chloride. Morphologic and histochemical findings in epidermal cells of human subjects who do not show allergic sensitivity or primary irritant reactions to mercuric chloride (0.1 per cent)

DCs-based therapies: potential strategies in severe SARS-CoV-2 infection

Pneumonia caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is spreading globally. There have been strenuous efforts to reveal the mechanisms that the host defends itself against invasion by this virus. The immune system could play a crucial role in virus infection. Dendritic cell as sentinel of the immune system plays an irreplaceable role. Dendritic cells-based therapeutic approach may be a potential strategy for SARS-CoV-2 infection. In this review, the characteristics of coronavirus are described briefly. We focus on the essential functions of dendritic cell in severe SARS-CoV-2 infection. Basis of treatment based dendritic cells to combat coronavirus infections is summarized. Finally, we propose that the combination of DCs based vaccine and other therapy is worth further study.

Elemental redistribution and ultrastructural changes in guinea pig epidermis after dinitrochlorobenzene (DNCB) exposure

Energy dispersive x-ray microanalysis and transmission electron microscopy were used to study ultrastructural and chemical changes occurring in the keratinocytes at the primary irritant dinitrochlorobenzene (DNCB) reaction. The results of the microanalysis showed a similarity between dose- and time-dependent effects of DNCB and were in accordance with the ultrastructural findings. With increasing cell injury (as judged by the ultrastructure) there was an increasing loss of phosphorus, potassium, and magnesium from the cells and an increase of cellular calcium content. Sodium and chloride were only moderately changed. Results recorded when the skin was exposed to a weak DNCB dose were in accordance with a stimulation of the basal keratinocyte cell population.

Corneal allograft rejection. The role of the major histocompatibility complex

The greater success of corneal transplantation compared to other organ transplants has led to the concept that the cornea is a site of "immunological privilege." Corneal cells possess the antigens of the major histocompatibility complex responsible for allograft rejection in other tissues (i.e., HLA antigens). The avascularity of the cornea accounts for the relative protection of the donor cornea from the immunological surveillance of the recipient. As the roles and functions of the major histocompatibility complex are unravelled, the mechanisms responsible for host sensitization, lymphocyte activation and allograft rejection are becoming better understood. In particular, the HLA-DR antigen in humans is believed to play an integral part in allograft rejection. Langerhans cells in human corneal epithelium have been shown to bear this antigen. Evidence suggests that these cells or similar HLA-DR-bearing cells in the cornea play a major role in corneal allograft rejection. In light of these advances in transplantation immunobiology, new methods of suppressing and possibly preventing allograft rejection in corneal transplantation are presented.

Langerhans cells as macrophages in skin and lymphoid organs

Properties of epidermal Langerhans cell were compared with those of a number of other dendritic cells in lymphoid organs and of mononuclear phagocytes. Among the dendritic "reticulum" cells included were indeterminate cells from the epidermis, interdigitating "reticulum" cells from T-dependent areas of lymphoid tissue and thymus, follicular dendritic cells of Nossal, and the dendritic cells described by Steinman and Cohn. Interdigitating cells with typical Birbeck granules, in the thymus and in the paracortices of lymph nodes, which are morphologically indistinguishable from Langerhans cells and indeterminate dendritic cells in the epidermis, appear to belong to the same system and possibly represent a subpopulation of "macrophages." On the basis of their similarity to these other dendritic cells, we believe Langerhans cells may function in antigen presentation, lymphokine production, provision of a microenvironment for T lymphocytes, and prostaglandin secretion.

Target role of Langerhans cells in mycosis fungoides: transmission and immuno-electron microscopic studies

Langerhans cells of the epidermis are "special" macrophages, as indicated by their expression of Fc and C3 receptors and Ia antigen. Functionally, they can replace macrophages in presentation of antigens to T cells and in the MLR. Ultrastructural and immunologic studies were carried out on epidermal samples of mycosis fungoides. As in contact allergy, apposition of lymphocytes to Langerhans cells was noted. Destruction of Langerhans cells appeared to act as the focus for the development of Pautrier microabscesses. This destruction was accompanied by ingress of histocytic cells, probably related to the stem cell population for Langerhans cells. The target cell role of Langerhans cells appears to be similar in contact allergy and mycosis fungoides.

An electron-microscopic study of basal cell carcinoma

Thirty-two basal cell carcinomas have been examined by electron microscopy. The majority exhibit cellular polymorphism and the most frequently encountered non-epithelial unit is the Langerhans cell. The nature of basal cell carcinoma and the function of the Langerhans cell are discussed in relation to this observation.

Immuno-electron microscopic studies of surface receptors and antigens of human Langerhans cells

A heteroantiserum, prepared in rabbits against fractionated cell membranes of a human B-lymphoblastoid cell line, was used to study the distribution of Ia antigen(s) in human epidermis. Indirect immunofluorescence staining demonstrated specific reactivity of dendritic supra-basal cells, consistent in location with Langerhans cells. Basally located cells were noted in biopsy specimens from vitiliginous skin and from the leukodermatous regions of halo naevi. The specificity of the reaction was confirmed at the ultrastructural level by means of ferritin labelling methods. Cell surface staining was confined in the epidermis to Langerhans cells. Fc and C3' receptors were studied by means of rosetting methods. Negative results were obtained on frozen sections, while 2-3% of cells formed rosettes when applied to an epidermal cell suspension.

Langerhans cells at the sites of vaccinia virus inoculation

Langerhans cells in the epidermis at the sites of vaccina virus inoculation were studied with the electron microscope. The cells contained unusually increased numbers of the Langerhans cell granules. Such abnormal Langerhans cells have not been described except for in histiocytosis X. Vaccinia virus particles were found in the Langerhans cells, where they were located individually or embedded in the granular matrix or in lysosomes.

A model implicating the Langerhans cell in keratinocyte proliferation control

A tentative model is presented which is based on existing data and our own cell kinetic and morphological observations in mice. The model suggests that the epidermal Langerhans cell plays a role in proliferation control of keratinocytes and may also act as an epidermal stem cell.

Effect of protective agent against lipid-solvent-induced damages. Ultrastructural and scanning electron microscopical study of human epidermis

The ultrastructural and relief (cyto-architectural) changes of human epidermis following exposure to a protective gel and acetone or kerosene were studied in healthy volunteers. Topical applications of acetone and kerosene on unprotected skin produced cell damage and a disorganized pattern in the upper layers of epidermis. The ultrastructural changes following acetone consisted of large paranuclear vacuoles, swollen mitochondria, and clumped tonofilaments. Severe disorganization with intense cytolysis and enlarged intercellular spaces occurred after exposure to kerosene. Scanning electron microscopy revealed edematous connified cells (corneocytes) following acetone exposure, whereas kerosene induced the occurrence of large lacunae in the swollen corneocytes. The application of a protective agent prior to solvent exposure substantially reduced the ultrastructural and relief changes of epidermal cells.