Cell membrane glycoproteins and Langerhans cells

Comparative study of the in situ immune response in oral and nasal mucosal leishmaniasis

Mucosal Leishmaniasis (ML) may occur in both nasal and oral mucosa. However, despite the impressive tissue destruction, little is known about the oral involvement. To compare some changes underlying inflammation in oral and nasal ML, we performed immunohistochemistry on mucosal tissue of 20 patients with ML (nasal [n = 12]; oral [n = 8] lesions) and 20 healthy donors using antibodies that recognize inflammatory markers (CD3, CD4, CD8, CD22, CD68, neutrophil elastase, CD1a, CLA, Ki67, Bcl-2, NOS2, CD62E, Fas and FasL). A significantly larger number of cells, mainly T cells and macrophages, were observed in lesions than in healthy tissue. In addition, high nitric oxide synthase 2 (NOS2) expression was associated with a reduced detection of parasites, highlighting the importance of NOS2 for parasite elimination. Oral lesions had higher numbers of neutrophils, parasites, proliferating cells and NOS2 than nasal lesions. These findings, together with the shorter duration of oral lesions and more intense symptoms, suggest a more recent inflammatory process. It could be explained by lesion-induced oral cavity changes that lead to eating difficulties and social stigma. In addition, the frequent poor tooth conservation and gingival inflammation tend to amplify tissue destruction and symptoms and may impair and confuse the correct diagnosis, thus delaying the onset of specific treatment.

The effect of stopping smoking on cervical Langerhans' cells and lymphocytes

OBJECTIVE

To investigate the effects of stopping smoking on cervical Langerhans' cells and lymphocytes.

DESIGN

Prospective intervention study.

SETTING

A large family planning clinic in central London.

POPULATION

Women volunteers prepared to attempt to give up smoking for six months. Their most recent cervical smear showed no abnormality greater than mild dyskaryosis.

METHODS

The women were seen at three-month intervals for six months. Reduction in smoking was assessed by self-reporting and validated by salivary cotinine concentrations. Colposcopy and a biopsy of a normal area were performed at the first and last visits. Any area of abnormality was also biopsied at the final visit. Langerhans' cells and lymphocytes were counted.

MAIN OUTCOME MEASURES

Proportional changes in counts of Langerhans' cells and lymphocytes with reduction in smoking.

RESULTS

Reduction in smoking by 20 to 40 cigarettes per day was significantly associated with a reduction of between 6% and 16% in counts of Langerhans cells, CD8 and total lymphocytes. Heavy smoking was significantly associated (P = 0.02) with an increased chance of persistent human papillomavirus infection. The presence of candida was associated with significantly higher counts of between 41% and 47% in total lymphocytes and CD8 lymphocytes. In contrast, the presence of anaerobic vaginosis was associated with significantly lower counts of between 16% and 30% in Langerhans cells, CD4 and CD8 lymphocytes.

CONCLUSIONS

This large intervention study has demonstrated a clear relationship between reduction in smoking and changes in cervical immune cell counts. Future studies need to take into account cytokine interactions, which recent studies suggest may be significant in the immune response to both human papillomavirus and cervical intraepithelial neoplasia and the ever-increasing complexity of the cell-mediated immune system of the cervix.

Langerhans cells in the development of skin cancer: a qualitative and quantitative comparison of cell markers in normal, acanthotic and neoplastic ovine skin

The distribution of Langerhans cells in normal, acanthotic and neoplastic ovine epithelium was examined using the enzyme marker Acetylcholinesterase (AchE) and monoclonal antibodies (MoAb) to CD1 (20.27) and MHC Class II (49.1 and 28.1) molecules. In normal skin, where Langerhans cells were regularly spaced within the basal layer, qualitative observations and direct pairwise testing showed that AChE was superior to the MoAb in detecting these cells. Significantly more (P < 0.01) dendritic cells were also detected with MoAb 49.1 than MoAb 20.27 or 28.1, suggesting differential expression of MHC Class II subsets and the presence of CD1- MHC Class II+ granule- dendritic cells in sheep analogous to indeterminate cells of man. In acanthotic skin, compared to normal skin, Langerhans cells were less numerous, irregular and more suprabasal in distribution and their morphology was occasionally swollen and indistinct. No difference was seen in the ability of AChE and MoAb in detecting Langerhans cells, however pairwise testing of markers did demonstrate that significantly more (P < 0.05) cells without dendritic processes were stained with MoAb 49.1 than with 20.27 or 28.1. In all squamous cell carcinomas examined dendritic cells that stained for AChE, CD1 or MHC Class II antigens were concentrated at the peripheral areas of neoplastic epithelium. Many dendritic cells were detected with MoAb to MHC Class II antigens, whereas CD1 and AChE positive dendritic cells were rare in tumor bearing tissue. The quantitative differences in the immunohistochemical staining of Langerhans cells between normal, acanthotic and neoplastic epithelium were consistent with ultrastructural studies. When compared with those of a newborn lamb, which had had very little exposure to antigens or ultraviolet radiation (UVR), the Langerhans cells of the aged sheep were deformed and contained far fewer Birbeck granules. The abnormalities were progressively more severe in acanthotic and neoplastic skin. These observed changes may have resulted from UVR induced damage and may be indicative of impaired function involved in the development of skin cancer.

Local immune response in endometrial carcinomas

OBJECTIVE

To determine whether Langerhans cells act as antigen-presenting cells in endometrial carcinomas and their related lesions.

SAMPLES

Frozen endometrial samples were obtained from 13 women with normal menstrual cycles, 3 postmenopausal women, 11 women with hyperplasia (simple 4, complex 4 and atypical 3) and 32 women with endometrial carcinomas.

MAIN OUTCOME MEASURES

Langerhans cells (CD1), T lymphocytes (CD4 and CD8), B lymphocytes (CD22), natural killer (NK) cells (CD57) and HLA-DR were all quantitatively assessed in endometrial samples using immunohistochemical method.

RESULTS

The numbers of Langerhans, CD4+, CD8+ and B cells were higher in the secretory phase than in the proliferative endometrium. The CD8+ cells appeared to be more plentiful than the CD4+ cells. When compared with the proliferative endometrium, the numbers of Langerhans cells were higher in hyperplasias and carcinomas. Most of Langerhans cells were HLA-DR+, showing a strong correlation with CD4+ cells in carcinomas. This suggests that MHC class II antigen restricted lymphocytes in carcinomas are activated by HLA-DR+ Langerhans cells. However, epithelial expression of HLA-DR in carcinomas did not show on association with high numbers of Langerhans and CD4+ cells. No correlation was observed between Langerhans cells and clinicopathologic features of carcinomas. In contrast, the number of NK cells significantly decreased in noninvasive carcinomas but increased in Grade 3 tumours.

CONCLUSION

Based on the above findings, Langerhans cells are considered to act as antigen-presenting cells in carcinomas, but it was not shown that they were activated by epithelial expression of HLA-DR in carcinomas.

Langerhans cells in oral mucosa of rhesus monkeys before and after infection by simian retrovirus-1 and simian immunodeficiency virus

To study the influence of experimental infection with simian retrovirus-1 and simian immunodeficiency virus on the number and distribution of Langerhans cells in oral mucosa of rhesus monkeys, 10 monkeys were intravenously inoculated with simian retrovirus-1, 7 with simian immunodeficiency virus, and 2 were mock-inoculated. Biopsies were taken from gingiva and cheek pouch before infection and at 1 (simian immunodeficiency virus group only), 4, and 7 months after infection. Langerhans cells were detected in frozen sections by immunohistochemistry with monoclonal antibodies Leu-6 and HLA-DR. The mean number of Langerhans cells per surface millimeter and square millimeter of epithelium was calculated under blind conditions. The results showed no statistically significant differences in the number or distribution of Langerhans cells in the three groups at the various time points of examination. Similarly, no differences were detected within any group over the observation period. Thus systemic infection of rhesus monkeys with either simian retrovirus-1 or simian immunodeficiency virus does not lead to a significant change in the number of Langerhans cells in oral mucosal epithelium.

The conjunctiva in acute and chronic mucous membrane pemphigoid. An immunohistochemical analysis

BACKGROUND

The mechanism of chronic progressive conjunctival cicatrization in mucous membrane pemphigoid is not well understood, and current therapy is often of limited use. Rapid progression of cicatrization follows exacerbations of clinical inflammation, and the investigation of immune mechanisms related to disease activity may provide a clue for more effective therapeutic strategies.

METHODS

The authors undertook an immunohistochemical study, using monoclonal and polyclonal antibodies in glycol methacrylate-embedded tissues, of epibulbar conjunctival biopsy specimens obtained from 20 patients with ocular cicatricial pemphigoid and from 12 matched healthy controls. The study patients were classified according to the ocular disease activity as acute ulcerative (n = 4), subacute (n = 8), and chronic (n = 8).

RESULTS

The composition of the subepithelial cellular infiltrate varied with disease activity. Acute disease was characterized by an abundance of macrophages and neutrophils. The number of T lymphocytes was significantly raised in all the disease groups, but were most marked in subacute disease. Of the T-cell subsets, there were more CD8- than CD4-positive cells observed, except in acute disease where there were equal numbers. Only approximately 5% of the T cells in all disease groups were activated as demonstrated by expression of interleukin-2 receptor. There was increased expression of major histocompatibility complex class II (MHC II) molecules on macrophages, fibroblasts, and other cells in all the groups. The number of B cells and natural killer cells was not increased. Staining for the fibrogenic cytokines, transforming growth factor-beta (TGF-beta), platelet-derived growth factor, and basic fibroblast growth factor was found in both pemphigoid patients and control persons, but the intensity of TGF-beta staining was significantly greater in acute disease.

CONCLUSIONS

The composition of the cellular infiltrate in the bulbar conjunctiva depends on clinical disease activity. The numbers of neutrophils and macrophages seem to reflect clinical disease activity. Fibrogenic cytokines, especially TGF-beta, may play an important role in the formation of conjunctival scar tissue.

Immunohistochemical and ultrastructural examination of histiocytosis X cells in pulmonary eosinophilic granuloma

We describe histological, immunohistochemical, and ultrastructural findings in pulmonary eosinophilic granuloma (PEG) from three patients. The specimens were taken by open-lung biopsy. The lesions of the lung were composed of histiocytic cells, macrophages and eosinophils. The histiocytic cells reacted positively with anti-S-100 protein antibody. The histiocytic cells had various types of Birbeck granules in the cytoplasm. The histiocytic cells were histiocytosis X (HX) cells considered to be derived from Langerhans cells. Sporadic mitosis of HX cells was observed. Some HX cells had migrated from the lesions into the alveolar spaces through the alveolar cell layers. In the lesions of PEG, HX cells have self-reproduction and migration capability.

Langerhans' cells in equine cutaneous papillomas and normal skin

Langerhans' cells (LC) were investigated immunohistochemically and electron microscopically in normal equine epidermis and 133 equine cutaneous papillomas experimentally induced in five 2-year-old Thoroughbred horses. Class II major histocompatibility complex antigen-positive dendritic LC were found in the normal epidermis and ultrastructurally had the characteristic Birbeck's granules. In the developing phase of the papillomas, LC were significantly decreased in number and size, indicative of a hypofunctional state. In the regressing phase of the papillomas, LC were markedly increased in number, especially at the epidermis-dermis junction. LC with long dendrites were rich in cytoplasm with well-developed cytoplasmic organelles, including Golgi apparatus, lysosomes, Birbeck's granules, and multivesicular bodies. These LC were hyperfunctional. An infiltration of many T lymphocytes was also observed at the epidermis-dermis junction.

Langerhans cells and subsets of lymphocytes in the nasal mucosa

Langerhans cells and different lymphocytes were studied in the nasal mucosa of 39 woodwork teachers and a control group of 14 healthy subjects. Ten of the woodwork teachers were sensitized as determined by skin prick test. A panel of different monoclonal antibodies was applied on the frozen nasal mucosal specimens. Intraepithelial CD1-positive dendritic cells were found in all specimens. However, there was no difference between the number of these Langerhans cells found in the study group and the number found in the controls. In every specimen the intraepithelial lymphocyte population was dominated by T lymphocytes, and there were relatively few B cells. Similarly the ratio between CD4- and CD8-positive lymphocytes in the study group and the controls was the same. In all specimens there was a dominance of T suppressor/cytotoxic cells compared with T helper/inducer cells. The study confirms that Langerhans cells are present in normal nasal surface epithelium, and suggests that there is no basic difference in the number of Langerhans cells between healthy persons, persons with nasal complaints, and persons with nasal allergy. The dominance of T lymphocytes in the epithelium may indicate the existence of a local cell-mediated immunity other than that associated with the regulation of IgE.

Langerhans cell histiocytosis of the female genital tract

Langerhans cell histiocytosis (LCH) of the female genital tract is rare. Four new cases are reported, and there is a review of the 38 cases in the literature. This disease may involve the vulva, vagina, cervix, endometrium, and ovary. Four distinct patient groups, segregated on the basis of initial presentation and subsequent anatomic extent of disease, were categorized as follows: (1) "pure" genital LCH, (2) genital LCH with subsequent multi-organ involvement, (3) oral or cutaneous LCH with subsequent genital and multi-organ involvement, and (4) diabetes insipidus with subsequent genital and multi-organ disease. Although involvement of the genital tract can occur at any age, it is most common in young adulthood. Clinically, LCH may mimic either primary neoplasia or various inflammatory lesions; the major pathologic differential diagnosis is venereal and other inflammatory diseases. The pure genital form may have a distinct nosologic position in the spectrum of LCH similar to the "pure," self-limited cutaneous histiocytosis seen in infants. There is no correlation between histologic findings and the outcome of the genital lesions. There is also no correlation between clinical presentation and/or the extent of involvement and outcome of genital lesions; complete regression, partial improvement, persistent lesions, and recurrences were seen in all four groups of patients. The treatment of genital LCH is not well defined and is highly individualized. Therapy has included surgery, radiation, topical corticosteroids, topical nitrogen mustard, systemic chemotherapy, and combination therapy; mixed results were obtained with all treatment modalities. Although no modality has been shown to yield a superior outcome, complete surgical excision is advocated as initial therapy.

Modulation of Langerhans cell surface antigen expression by recombinant cytokines

This study examined the influence of cytokines on surface antigen expression by gingival Langerhans cells (LC) in organ culture, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) upregulated the expression of CD1a, HLA-DR and HLA-DP antigens on LC. TNF-alpha, interleukin-4 (IL-4), and transforming growth factor beta (TGF-beta) suppressed CD29 expression, while other cytokines, including interleukin-3 and granulocyte-macrophage colony stimulating factor, were without effect. No cytokines induced CD3, CD4, CD23, CD25 or CD45 RA antigen expression in organ culture. Since TNF-alpha and IL-6 can be secreted by keratinocytes, these molecules, together with interleukin-1, are likely to play a role in the local control of LC number and function within the epithelial milleu. Thus, alterations in cytokine secretion by keratinocytes may at least in part be responsible for variations in LC number and antigen expression which occur in oral mucosal disorders.

The activation of Langerhans cells in oral lichen planus

The numbers of CD1, HLADR, HLADP and HLADQ positive, intraepithelial, dendritic cells were compared in lesions of oral lichen planus and normal oral mucosa using an immunoalkaline phosphatase technique. In normal mucosa, there were equal numbers of CD1 and HLADR positive cells but significantly fewer cells were positive for HLADP (P less than 0.001) and HLADQ (P less than 0.05). In lichen planus, the cells appeared more dendritic and equal numbers of CD1, HLADR, HLADP and HLADQ positive cells were found, with significantly more HLADP (P less than 0.01) and HLADQ (P less than 0.05) positive cells than in normal mucosa. There was no change in the number of CD1 and HLADR positive cells. These results show that although there is no change in the total number of Langerhans cells (CD1 positive cells) in lichen planus, there is an increase in Class II major histocompatibility antigen expression. This suggests that in lichen planus, Langerhans cells are immunologically active and play a role in lesion development.

Comparison between the L-DOPA histofluorescence procedure and the indirect immunofluorescence with anti-T6 and -HLA-DR monoclonal antibodies in visualizing Langerhans cells of human epidermis

In order to assess the reliability of the L-DOPA histofluorescence (HF) procedure in visualizing the Langerhans cells (LC) of human epidermis, serial sections of human normal skin samples have been incubated with L-DOPA and alternatively processed for the L-DOPA HF and the indirect IF with anti-T6 and anti-HLA-DR monoclonal antibodies. Results demonstrated a good correlation of LC labelling; comparison between the number of L-DOPA positive (T6 positive and L-DOPA positive) HLA-DR positive dendritic cells did not show statistically significant differences. Therefore, the L-DOPA HF represents a valuable method for detecting LC in the human normal epidermis.

Immunohistochemical demonstration of histiocytes in normal ectocervical epithelium and epithelial lesions of the uterine cervix

The numbers of Langerhans cells and lysozyme-positive macrophages were assessed quantitatively in normal ectocervical epithelium, cervical intraepithelial neoplasia (CIN), microinvasive squamous cell carcinoma (MICA), clinical invasive squamous cell carcinoma (CICA), and koilocytotic atypia using the avidin-biotin-peroxidase complex (ABC) method. The distribution of Langerhans cells was different from that of lysozyme-positive macrophages in that the former were intermingled with the cervical lesion, while the latter were present mainly surrounding the cervical lesion and/or on the edge of the cervical lesion. The numbers of Langerhans cells and lysozyme-positive macrophages in CIN were significantly larger than those in normal ectocervical epithelium and significantly smaller than those in invasive squamous cell carcinoma (MICA + CICA). Langerhans cell number significantly increased as the grade of CIN advanced. In contrast, the number of lysozyme-positive macrophages did not differ significantly between progressive grades of CIN. As for koilocytotic atypia, the numbers of Langerhans cells and lysozyme-positive macrophages in koilocytotic atypia were significantly greater than those in normal ectocervical epithelium but did not differ significantly from those in CIN 1 and CIN 2. With respect to stromal lymphoid infiltration, invasive squamous cell carcinoma with moderate or dense stromal lymphoid infiltration showed significantly greater numbers of Langerhans cells and lysozyme-positive macrophages than that with no or scattered stromal lymphoid infiltration, but such a correlation was not found in CIN.

Immunophenotypic analysis of the inflammatory infiltrate in ocular cicatricial pemphigoid. Further evidence for a T cell-mediated disease

Ocular cicatricial pemphigoid (OCP) is characterized by the deposition of immunoglobulin and complement along the conjunctival epithelial basement membrane zone (BMZ). In order to further elucidate the cellular populations of the local inflammatory infiltrates, the authors used a panel of monoclonal antibodies in cryostat tissue sections to delineate T cell subsets, B lymphocytes, dendritic cells, and macrophages in six patients with OCP. In comparison with matched controls of the epibulbar conjunctiva, the authors discovered a threefold increase in T lymphocytes within the epithelium and a 20-fold increase within the substantia propria. In contrast with the normal-standing population of conjunctival T lymphocytes, there were activated interleukin 2 receptor (IL-2R)-positive lymphocytes in both the epithelium and the substantia propria. Macrophages were the second most common cells in the substantia propria, accounting for 12.7% of the mononuclear population--a threefold increase over the normal percentage. B cells and plasma cells, normally absent from epibulbar conjunctiva, were the next most prominent populations, constituting 6.9 and 4.6%, respectively, of all mononuclear cells. Dendritic cells which process antigen locally constituted only 1.2% of the mononuclear cell population, but were increased 25-fold over normal controls. By elaborating cytokines that promote fibroplasia, the T cells in OCP may be effector cells along with macrophages and other inflammatory cells in bringing about scarification of the substantia propria, and may furthermore be responsible for an immunoregulatory defect that allows local B lymphocytes to produce autoantibodies to the BMZ.

The Langerhans' cells

The morphological, enzymatical, immunocytochemical and functional properties of Langerhans' cells are briefly reviewed. Langerhans' cells are located mainly in the squamous stratified epithelia, but are also present in the thymus and in superficial lymphnodes. At the ultrastructural level, they are characterized by unique cytoplasmic organelles, the Birbeck granules, whose function is still unknown. Langerhans' cells possess strong ATPase activity and are weakly positive for alpha-naphtyl acetate esterase and for acid phosphatase; they are immunoreactive for CD1a (T6), class II MHC antigens and S-100 protein. In some pathological conditions, like dermatopathic lymphadenopathy and Langerhans' cell histocytosis, Langerhans' cells also are characterized by the expression of monocyte-macrophage antigens. Langerhans' cells act as antigen-presenting cells to T lymphocytes; their functional capacity is strictly dependent on the levels of expression of class II MHC antigens. Langerhans' cells are of bone marrow origin and are derived from a circulating precursor which is probably related to the monocyte.

Ultrastructural characteristics of the contact zones between Langerhans cells and lymphocytes

The present work was carried out to look for the ultrastructural substrate of the contact zones between Langerhans cells and lymphocytes. A high resolution electron microscopic analysis of the contact zones between Langerhans cells and lymphocytes was performed. The material used for this study was obtained from experimental contact dermatitis in mice, and human cervical squamous carcinoma and mycosis fungoides. Three types of cell-cell binding were found. Type I is a junction-like structure characterized by the presence of intercellular bridges. It is suggested that this contact might represent a fixation mechanism between the two cells. Type II is characterized by a glycocalyx-glycocalyx continuity. An immunological function--recognition and antigen presentation--is proposed for this type of contact. Type III is a septilaminar tight contact area which seems to be a gap junction. It is suggested that all these types of physical contact might be the morphological expression of interaction between antigen presenting cells and lymphocytes.

Identification of CD4+, 2H4+ (T8 gamma +) suppressor-inducer cells in normal human epidermis and superficial dermis

Immunohistological staining of frozen sections of normal human skin demonstrated the presence of significant numbers of mononuclear cells expressing novel epitopes associated with CD4-positive suppressor-inducer functions. The cells were located around superficial vessels and within the basal layers of the epidermis and hair follicles. The antigen identified by the various antibodies has been shown to be functionally important in the induction of various suppressor cells capable of abrogating B cell responses to pokeweed mitogen. The presence in the skin of cells with possible down-regulatory functions in the immune response may be significant with respect to surveillance against neoplasms and control of appropriate responses to infectious agents.

Distribution of Langerhans cells in clinically healthy human gingival epithelium with special emphasis on junctional epithelium

Twenty-one biopsies of clinically healthy marginal gingiva from children, who performed conventional oral hygiene but received no additional professional prophylaxis, were studied in order to obtain information on distribution and density of Langerhans cells (LC) in the oral gingival epithelium (OGE), the sulcular epithelium (SE) and the junctional epithelium (JE). A simple freeze-separation technique was found to create acceptable histomorphology of JE in specimens obtained adherent to teeth, while partially and non-adherent ones were rejected. The majority of LC in OGE were highly dendritic and stained intensively with OKT6 monoclonal antibodies. The distribution was network-like with a density of 21.0 +/- 3.2 LC/0.1 mm2 cross-sectional epithelial area. A similar although less dense distribution was found in SE (8.6 +/- 3.0 LC/0.1 mm2). These observations confirm previous findings. In JE 2 groups of LC were identified: 1) Weakly stained LC with very few and short dendrites distributed in a scattered way (2.8 +/- 1.4 LC/0.1 mm2) in the apical three-fourths of JE in most specimens. Present evidence suggests that these cells might be immature cells of Langerhans lineage. 2) Clusters of LC (9.4 +/- 2.9 LC/0.1 mm2) with dendrites of moderate lengths and numbers and a varied fluorescence intensity; they were found in a few specimens in the coronal one-fourth of JE and at the border zone to SE. Such clusters might represent genuine variation in the distribution of LC or reactions to initial/early plaque formation.

Letterer-Siwe disease: immunohistochemical evidence for a proliferative disorder involving immature cells of Langerhans lineage

The morphological, ultrastructural and immunophenotypic properties of Histiocytosis-X (H-X) cells were investigated in a lymph node involved by Letterer-Siwe (L-S) disease. H-X cells were T6+ (CD1a), S-100+, T4+ (CD4) and HLA-DR+; in addition they were consistently T11+ (CD2) and were stained by antibodies directed against receptors for transferrin (T9), C3bi (OKM-1/CD11b), IgG-Fc (Leu-11/CD16) and Interleukin-2 (IL-2R/CD25). On immunostained cytosmears, T6+ cells were highly polymorphic and a prominent fraction (45%) showed immature morphology, characterized by lymphoid appearance. Cells expressing macrophage markers (ANAE, AACT, Leu-M3/CD14, PAM-1) were 10-fold fewer than T6+ cells and did not show a lymphoid morphology. At TEM level, H-X cells were characterized by poor content of LC granules and by the presence of myelin-like laminated bodies and of lysosome-like dense bodies. The immunophenotypic properties of H-X cells were compared to those of epidermal Langerhans cells (LCs) and of LCs present in lymph nodes of three cases of dermatophatic lymphadenitis. Epidermal LCs were T6+/HLA-DR+, and sometimes faintly T4+. Lymph node LCs were T6+, S-100+, T4+, HLA-DR+, and showed the same variety of surface receptors detected in H-X cells; furthermore, in a case with massive infiltration of the paracortex by T6+ cells, lymph node LCs were faintly T11+ and some of the T6+ cells had lymphoid aspect. Our findings suggest that the H-X cell population of L-S disease is not homogeneous, but is composed of discrete cell subsets with distinctive antigenic and morphological traits closely resembling those of cells of LC lineage at different maturational stages.

The regulation of Langerhans cell T6, DR and DQ antigen expression: an hypothesis

A hypothetical model of the maturation pathway of Langerhans cells (LC) within an epithelial environment is presented. This model is based on in vitro studies using human gingival organ culture. In this model, T6 (CD1) antigen is induced on a T6(-) intraepithelial population by Interleukin-1 secreted by epithelial cells. This process is abrogated by a locally produced Interleukin-1 inhibitor, ILS. These T6(+) LC then express first HLA-DR and subsequently HLA-DQ surface antigens under the influence of either lipopolysaccharide or gamma interferon. The induction of these Class II antigens on LC is inhibited by prostaglandin E2. It is postulated that these Class II antigen positive LC are then available to function as antigen presenting cells. This hypothesis is consistent with in vitro studies and several in vivo observations. The basis of the hypothesis is the demonstration that locally produced factors may exert an influence on LC behaviour within an epithelial environment.

Dendritic cells in cutaneous, lymph node and pulmonary lesions of sarcoidosis

To determine whether dendritic cells (DC) are a consistent feature of lesions of sarcoidosis, we have used monoclonal antibodies to identify the HLA-DR-expressing populations of cells in cryostat sections of 15 lymph node, pulmonary and cutaneous lesions. The commonest HLA-DR positive cells in granulomas were epithelioid and giant cells, although lymphocytes within granulomas and tissue macrophages around them were also positive. Dendritic cells with Langerhans cells (NA1/34+ = OKT6+) and interdigitating cell (RFD1+) phenotype were consistently associated with granulomas only in skin lesions. In lymph nodes, interdigitating cells (NA1/34-/RFD1+/HLA-DR++) were confined to paracortical zones as in normal nodes, although a small area of NA1/34+/RFD1+ cells was found in one of three nodes. In lung lesions NA1/34+/RFD1+ dendritic cells were uncommon or absent, except in one chronic case. We conclude that while sometimes present in extracutaneous sites, DC are not an essential feature of sarcoid lesions, and that cells of the classical macrophage group are the most significant HLA-DR-expressing population. We suggest that the presence of DC in lesions of sarcoidosis may indicate an immunological response distinct from that causing granulomas to form. The variability of their involvement may have immunoregulatory significance.

Morphogenesis and malformations of the skin NICHD/NIADDK research workshop

Developmentally caused skin malformations constitute a spectrum of birth defects, some of which can be recognized prenatally by morphologic or biochemical means. The number of prenatally diagnosable skin diseases could be greatly expanded with an increased understanding of the molecular and cellular bases of skin development and the mechanisms that result in the generation of skin defects. The National Institute of Child Health and Human Development and the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, therefore, sponsored a workshop that recommended basic biologic studies combined with clinical investigations of normal and abnormal cutaneous development set forth in this article. Investigations resulting from these research recommendations are intended to contribute to the knowledge that should aid in the prevention of developmentally caused skin deformities.

Postnatal colonization of porcine lung capillaries by intravascular macrophages: an ultrastructural, morphometric analysis

Lungs of newborn and of 7- and 30-day-old pigs were fixed at total capacity by a standardized procedure. Stereologic morphometry was applied to random ultrathin sections of parenchyma. Relative volume density, absolute volume, and capillary surface coverage of intravascular macrophages as well as parameters of relative morphometric diffusion capacity of lungs were assessed. Intravascular macrophages occupied up to 25% of capillary volume in 30-day-old pigs compared with 6% in newborn pigs; this was a 14-fold increase of absolute volume. In 30-day-old pigs, 16% of capillary surface was covered with closely adherent intravascular macrophages in contrast to only 2% in newborn pigs. Determinators of morphometric diffusion capacity were similar in all pigs. Greater thickness of the arithmetic and harmonic mean air-blood tissue barrier in 30-day-old pigs (with included thickness of intravascular macrophages) compared with air-blood tissue barriers (without intravascular macrophages) was not statistically significant. The relative difference of arithmetic mean was larger than the difference of harmonic mean, and reflected preferential adherence of intravascular macrophages to the thick portion of the air-blood tissue barrier. Our findings confirm morphologic observations of perinatal colonization of the porcine lung by monocytes that replicate and differentiate into large, highly phagocytic, resident, intravascular macrophages. Preferential adherence to sites where basal laminae of capillary endothelium and alveolar epithelium were separated by interstitium may explain the minimal morphometric impact of intravascular macrophages on the air-blood tissue barrier thickness. This location would be expected to have less effect on gas diffusion than location of intravascular macrophages on the thin side of the air-blood barrier.

An erythematous maculopapular eruption in macaques infected with an HTLV-III-like virus (STLV-III)

A cutaneous maculopapular eruption has been previously described in humans infected with HTLV-III/LAV, the etiologic agent of acquired immunodeficiency syndrome. In this study, rhesus monkeys were prospectively examined after infection with an HTLV-III-like virus (STLV-III) to ascertain the incidence and clinical course of gross and histologic alterations of the skin. Between 1-3 weeks after inoculation, 83% of infected animals developed a transient cutaneous maculopapular eruption of the face, groin, and trunk. Histologically, the affected skin was characterized by a superficial perivascular infiltrate of mononuclear cells with associated endothelial cell hypertrophy and degeneration. This eruption preceded opportunistic infections, neoplasms, and other overt clinical signs commonly associated with an immunodeficiency syndrome. The findings suggest that STLV-III infection in the rhesus monkey closely simulates that which occurs in HTLV-III-infected individuals, and that the skin may represent a site of altered immunoregulation early in the course of this disease.

Lymphocytic subpopulations in the normal human conjunctiva. A monoclonal antibody study

Monoclonal antibodies were used to analyze the lymphocytic subpopulations in frozen tissue sections of normal human conjunctiva (epibulbar, tarsal, and forniceal). The overwhelming majority of lymphocytes were T-cells (Leu1+ and OKT8+). In the epithelium, the predominant cell type was the OKT8+ cytotoxic/suppressor cell, whereas in the substantia propria, helper T-cells (Leu3a/3b+) equalled suppressor T-cells. T-cells outnumbered B-cells 20-fold; the letter cells were detected only in the substantial propria, particularly in the fornices, and not in the epithelium. Plasma cells, as identified by OKT10 staining, were completely absent except in the accessory lacrimal glands of Krause. Langerhans' cells, identified by OKT6 and HLA-DR (la) staining, were observed in the epithelium of all conjunctival regions. Our findings suggest that the reactivity of B-lymphocytes and plasma cells is heavily damped down by T-lymphocytes, thus allying the conjunctiva to other mucosal membranes and the skin as heavily immunoregulated tissues.

A comparison of conjunctival and nonocular dendritic cells utilizing new monoclonal antibodies

Langerhans cells belong to the dendritic cell family. Their presence in the conjunctiva and cornea has been demonstrated by means of various membrane and cytoplasmic markers. Utilizing OKT6, a monoclonal antibody that specifically binds to Langerhans cells in conjunction with la histocompatibility antigens (HLA-DR), and a new panel of monoclonal antibodies, we compared the population density and characteristic phenotypes of Langerhans cells in normal conjunctiva with those in normal epidermis. A greater density of Langerhans cells was noted in epidermis in comparison with conjunctiva. Various areas of the conjunctiva and cornea were mapped for Langerhans cell distribution. The T6/la ratio of Langerhans cells in conjunctiva was notably different from that in skin. Utilizing the Prolm2 marker, we identified non-Langerhans dendritic cells in the substantia propria and in the basilar epithelium of the conjunctiva, antigen-processing cells probably identical to the interdigitating dendritic cells of lymph nodes.

Ontogeny of Langerhans cells in human embryonic and fetal skin: expression of HLA-DR and OKT-6 determinants

Langerhans cells (LCs) have been identified in human skin by 10 weeks estimated gestational age (EGA), but it was not known when they first enter the epidermis or acquire HLA-DR, OKT-6, and ATPase reactivity. We assayed for LCs in human embryonic and fetal skin by using immunolabeling and histochemical techniques on epidermal sheets. HLA-DR+ and ATPase+ LCs were present in the epidermis by 6-7 weeks EGA, the youngest tissue examined. Most LCs were OKT-6- until about 12 weeks EGA when they underwent a dramatic increase in OKT-6 reactivity. Although LC densities between 50-100 days were statistically similar (100 cells/mm2 of epidermis), LCs early in development were smaller, less dendritic, and phenotypically heterogeneous. We conclude that LCs migrate into the epidermis during the first trimester and resemble the adult phenotype by the second trimester, long before the immune system is fully activated.

Leu-6-expressing cells in lymph nodes: dendritic cells phenotypically similar to interdigitating cells

Leu-6 is an antigen expressed by immature T cells, Langerhans cells, and indeterminate cells, the latter two of which are dendritic cells found predominantly within the skin. In dermatopathic lymphadenopathy, the paracortex is expanded by T cells and dendritic cells, including Langerhans cells. While the paracortex also contains Leu-6+ cells, the nature of such cells in lymph nodes has been controversial. To determine the characteristics of Leu-6+ paracortical cells, their morphologic, antigenic, and enzymatic features were studied in lymph nodes showing dermatopathic lymphadenopathy or reactive follicular hyperplasia. Immunologic studies with plastic, frozen, and paraffin sections demonstrated a dendritic cell morphology, a dendritic cell lineage phenotype (L3B12+, HLA-A,B,C+, HLA-DR+, S-100+), and the absence of T-cell lineage phenotype. These findings were corroborated by the enzymatic phenotype of these cells observed in plastic sections (membrane ATPase+, weak paranuclear acid phosphatase+, weak paranuclear alpha-napthylacetate esterase+). Although all paracortical dendritic cells were otherwise identical, only a subset of these cells were Leu-6+. The close phenotypic similarity between these Leu-6+ and Leu-6- paracortical dendritic cell subsets suggests a close ontogenetic relation. Furthermore, the greater abundance of the Leu-6+ subset in dermatopathic lymph nodes than in nodes exhibiting only reactive follicular hyperplasia, in conjunction with the presence of Leu-6+ dendritic cells within the sinuses of dermatopathic lymph nodes, suggests that at least some of the paracortical Leu-6+ cells are Leu-6+ Langerhans cells or indeterminate cells derived from the skin via the afferent lymphatics.

Immunohistochemical demonstration of p24 HTLV III major core protein in different cell types within lymph nodes from patients with lymphadenopathy syndrome (LAS)

The p24 protein is the major core protein of LAV/HTLV III which is the putative agent of the lymphadenopathy syndrome. By the use of an anti-p24 monoclonal antibody we have studied the presence of LAV/HTLV III infected cells in 20 lymph nodes obtained from lymphadenopathy syndrome patients: 14 lymph nodes were characterized by prominent follicular hyperplasia consistent with the early phase of the syndrome and six lymph nodes presented marked regressive changes. Cells positive for p24 were detected in 8/14 lymph nodes with hyperplastic changes and in 1/6 lymph nodes with regressive changes. Positive cells were most often located in germinal centres and were mainly characterized by a lymphoid morphology. However, immunoreactivity for p24 protein was also occasionally observed in some histiocytic-like cells and in high endothelial cells of post-capillary venules, suggesting that these 'accessory cells' also play a role in the early phases of the lymphadenopathy syndrome.

Cytotoxic T lymphocytes and phenotypically abnormal epidermal dendritic cells in fixed cutaneous eruptions

Fixed cutaneous eruptions are erythematous plaques or bullae that recur, often after drug ingestion, at precisely the same cutaneous sites. The study of this condition may provide insight into the mechanisms responsible for regionally localized, immunologically mediated dermatoses. Biopsy specimens from both advancing borders and established centers of fixed eruptions were studied by immunofluorescence microscopy, light microscopy (1-micron sections), and transmission electron microscopy, and with a panel of monoclonal antibodies to Langerhans cells and subsets of T lymphocytes. The dermal inflammatory infiltrates of the advancing edges of the lesions were composed predominantly of OKT4/Leu-3a-positive lymphoid cells in perivascular array. In more established regions (the centers of the lesions), the majority of mononuclear cells were OKT8-positive lymphocytes disposed along the dermal-epidermal junction and migrating into the epidermis through focal defects in the basement membrane. In these areas, keratinocyte reactivity for anti-HLA-DR antibody and the apposition of intraepidermal lymphocytes to degenerating keratinocytes were observed. T6-positive epidermal dendritic cells were observed in normal numbers in the epidermis, although extensive study failed to reveal characteristic Langerhans cell granules within these cells. It is concluded that fixed cutaneous eruptions are characterized by an early vascular phase involving lymphocytes with helper/inducer phenotypes, and a later epidermal phase involving cytotoxic/suppressor cells. Potential effector cells with the phenotypic characteristics of cytotoxic T cells appear to represent important mediators of the epidermal damage characteristic of fixed cutaneous eruptions. Morphologically abnormal epidermal dendritic cells may contribute to regionally altered antigen presentation and may thus be relevant to the recurrence of lesions at identical cutaneous sites.

Expression of activation antigens by T cells infiltrating basal cell carcinomas

The association of T lymphocytes and dendritic cells with the stromal mononuclear cell response to basal cell carcinomas has led to speculation that cellular immunity may, in part, regulate the growth and development of this neoplasm. It has not been established, however, whether these T cells are functionally competent, or simply coincidental bystanders. We examined the immunologic phenotypes of mononuclear cells in 32 lesions of basal cell carcinoma obtained from 26 patients. The majority of infiltrating mononuclear cells were T cells that were equally distributed between the helper/inducer (Leu 3a+) and cytotoxic/suppressor (Leu 2a+) subtypes; a minority of cells were dendritic and expressed Leu 6 antigen. Virtually all T cells and dendritic cells were HLA-DR+, and many (greater than 30%) of the T cells expressed antigens consistent with stages of ongoing activation (T9, T10). TS2/7, a novel monoclonal antibody recently documented to identify activation-specific subcomponents of 210/165/130 kD glycoprotein complex present on the surface of mitogen- or alloantigen-stimulated human T cells, was also used. Greater than 50% of the T cells observed were TS2/7+. These observations provide in situ immunomorphologic evidence of stromal T cell activation in association with basal cell carcinomas, and suggest a role for active and ongoing cellular immune mechanisms as a determinant of local biological behavior of this neoplasm.