The antigen-presenting function of human Langerhans cells

Células de Langerhans no epitélio da prega vocal humana: estudo imunoistoquímico

Células de Langerhans (CL) são um tipo de células dendríticas que têm funções que envolvem apresentação de antígeno e a estimulação de resposta T dependente. Elas representam aproximadamente 4% das células do epitélio laríngeo. OBJETIVO: Identificar a presença de CL no epitélio das pregas vocais, comparar suas subpopulações, bem com comparar a capacidade de quatro marcadores imunoistoquímicos. FORMA DE ESTUDO: Experimental. CASUÍSTICA E MÉTODO: Seis cadáveres, 3 homens e 3 mulheres foram estudados. Foram analisadas amostras de pele e das pregas vocais coradas e imunomarcadas para vimentina, proteína S-100, CD-68 e fascina. Após análise histológica, foi realizado o teste t de Student e análise de variância no estudo estatístico. RESULTADOS E CONCLUSÕES: Foi possível identificar a presença de CL no epitélio das pregas vocais de humanos não fumantes de ambos os sexos. A fascina, a vimentina o CD-68 mostraram-se bons marcadores das CL, enquanto a proteína S-100 teve estatisticamente menor poder de marcação tanto na prega vocal (p=0,01) como na pele (p=0,02). Foi possível identificar três diferentes subpopulações de CL presentes tanto na prega vocal como na pele destes indivíduos, contudo apenas na pele observarmos maior quantidade estatisticamente significante na camada basal do epitélio.

Langerhans' cell count and HLA class II profile in cervical intraepithelial neoplasia in the presence or absence of HIV infection

OBJECTIVES

The progression of immunosuppression in human immunodeficiency virus (HIV)+ women has been correlated with elevated incidence of squamous intraepithelial lesions (SIL), probably indicating the role of local immune milieu. In this study, we analysed S100, and HLA class II molecule expression in cervical biopsies according to HIV status, to the severity of SIL and to human papillomavirus (HPV) type.

METHODS

Biopsies from 34 HIV+ and 44 HIV- patients with normal cervix or low- or high-grade SIL were studied. Langerhans' cells (LC) (S100), HLA class II and HLA-DQ molecules were evaluated by immunohistochemistry. HPV detection was performed using polymerase chain reaction (PCR). For statistical analysis Mann-Whitney (P< or =0.05) and Spearman test were used.

RESULTS

Epithelial S100 and HLA class II density were significantly increased with the severity of lesion (P=0.032; P=0.005). Epithelial S100+ increased in HPV+ (P=0.038), and HLA class II density decreased in HPV 16+ (P=0.035) or 18+ (P<0.0001) samples. HIV infection was associated with increased stromal S100+ (P=0.0005) and decreased HLA class II densities (P=0.0001). Decreased stromal S100+ was observed in women with CD4<500 cells/microl (P=0.050). Among HIV+ patients with SIL, the lowest S100 and epithelial HLA class II densities were detected in women with CD4<200 cells/microl (P=0.045).

CONCLUSIONS

After the establishment of AIDS, increased numbers of immature LCs and a reduction in HLA class II occurred, possibly turning the cervical milieu more favourable to HPV persistence. HPV 16 and 18 infections may interfere with the antigen presenting activity, possibly as an evasion mechanism.

Contact dermatitis: clinics and pathology

Contact dermatitis or eczema is a polymorphic inflammation of the skin. It occurs at the site of contact with irritating or antigenic substances. In the acute phase there is occurrence of itching erythema, papules, and vesicles, whereas in the chronic phase there is dryness, hyperkeratosis, and sometimes fissures. Contact dermatitis can be divided into irritant and allergic types. Allergic contact dermatitis is a type-IV T-cell-mediated reaction occurring in a sensitized individual after contact with the antigen/allergen. Such antigens are usually low molecular weight substances (MW approximately 500), called haptens; 3000 contact allergens are known. The diagnosis of contact allergy is made on the basis of the history, clinical findings, and a positive epicutancous test result. Allergic, but not irritative, contact dermatitis can spread beyond the area of contact to other body parts. Eczematous lesions are characterized by a mononuclear infiltrate consisting mainly of T cells in the dermis and epidermis, together with an intercellular epidermal edema that is. spongiosis. In allergic contact dermatitis, skin-applied antigen is taken up by epidermal Langerhans cells and transported with the afferent lymph to the regional lymph nodes. Here, naive T lymphocytes are sensitized to become antigen-specific effector T cells, which then leave the lymph node, enter the circulation, and are recruited to the skin by means of specific cell surface molecules, to form the infiltrates. Cytokines released by infiltrating T cells eventually cause keratinocyte apoptosis.

Glycodelin-A expression in the uterine cervix

OBJECTIVE

Local immunosuppressive factors in the uterine cervix infected by human papillomavirus are felt to facilitate the malignant transformation process. Glycodelin-A is an immunosuppressive peptide found in several tissues of müllerian origin, most notably the pregnant and decidualized endometrium. Its expression in the uterine cervix has not been defined but could theoretically contribute to the immunopermissive environment of the cervix. To determine whether glycodelin-A is found in the cervix we examined the squamous and endocervical epithelia from both normal and neoplastic cervical specimens from 14 women.

METHODS

Immunohistochemisty identification of glycodelin-A was performed on archival paraffin-embedded sections from 10 hysterectomies and 4 cone biopsies. Sections were evaluated and staining was scored as negative, positive, or strongly positive with a separate score for the squamous and glandular components of the cervix.

RESULTS

Eleven of 14 cases, 79%, demonstrated positive staining of the squamous epithelium. Glycodelin-positive cases included hisologically normal (n = 4; 3 strongly positive, 1 positive) as well as dysplastic (n = 5; 1 strongly positive, 2 positive, and 2 negative) and malignant squamous cells (n = 5; 1 strongly positive, 3 positive, and 1 negative). Normal glandular epithelia were negative in all cases but 1, which demonstrated significant squamous and tubal metaplasia of the endocervical glands involved.

CONCLUSION

Glycodelin-A is found in the squamous epithelium of both the histologically normal and the neoplastic cervix. Further characterization of these results will focus on the possible immunosuppressive effect glycodelin-A may have in the cervix.

Evaluation of Langerhans' cells in the cervical epithelium of women with cervical intraepithelial neoplasia

OBJECTIVE

Cervical infection with human papillomavirus (HPV) results in a more permissive environment for malignant transformation. In squamous epithelia the Langerhans' cell (LC) is responsible for antigen presentation. Studies that use S-100 immunostaining demonstrate low LCs in cervical intraepithelial neoplasia (CIN) while those that use other methods have shown normal numbers of LCs. This observation led us to postulate that a defect in S-100 proteins, not a simple decrease in LC number, may be the cause of immune suppression. To evaluate this we identified LCs in the cervix of women with HPV/CIN in a prospective fashion using two antibodies, S-100 and CD1, each targeting a different element of the LC.

METHODS

Paired biopsies of the cervix were taken, one paraffin embedded for S-100 and the other snap frozen for CD1 staining. LCs were counted and expressed as the number of cells per millimeter of epithelium. Analysis of variance was used to assess differences between counts in normal, low-grade, and high-grade lesions. HPV was tested by hybrid capture.

RESULTS

S-100 LCs were significantly reduced in dysplasia, LG 8.6 and HG 6.0, compared to normal at 16.7 cells/mm (P = 0.04). S-100 LCs were reduced in HPV-infected cases at 5.9 vs 12.8 cells/mm in HPV negatives (P = 0.02). Acute inflammatory infiltrates were associated with increased S-100 LCs independent of pathology. CD1 LCs were not significantly altered by any parameters tested.

CONCLUSIONS

HPV/CIN may exert an immunosuppressive effect by decreasing the S-100 LCs. The association of S-100-positive LCs coupled with cervical inflammatory changes suggests an important function of the S-100 proteins in the development of an anti-HPV response.

Tattooing increases the number of Langerhans cells in skin: an immunocytochemical study

Tattooing is an act of permanent marking of the skin with indelible patterns by pricking and inserting pigments. Langerhans cells (LCS) are dendritic cells normally present in suprabasal layers of the epidermis of the skin. To assess whether there were any effects caused by the tattooing on Langerhans cell population and cutaneous nerves, skin from affected areas (n = 15) was compared with controls (n = 10). Frozen sections were immunostained with antisera to S-100. No discernible change either in distribution or in number of Langerhans cells and nerves was seen upon comparison with control skin taken from different areas, but all of the specimens taken from affected areas had a significant increase in the number of Langerhans cells (p < 0.001) even after several years of tattooing with no change in the cutaneous nerves. Thus, the study shows persistent stimulation of Langerhans cell population in tattooed skin.

Langerhans cells in normal and pathological vocal cord mucosa

The Langerhans cells in samples of histologically normal and pathological vocal cord mucosa were counted after identification using S-100 polyclonal antibody. Langerhans cells were commonly seen in vocal cord polyp epithelium but were infrequent in normal cord mucosa. They were also identified in samples of squamous carcinoma, severe dysplasia and chronic inflammation.

Depletion of Langerhans cells in cervical HPV infection is associated with replication of the virus

We studied the quantity of Langerhans cells in 36 patients with cervical human papillomavirus (HPV) infection. Significantly fewer Langerhans cells (p < 0.05) were found in patients with compared to those without DNA tetraploidy. Similarly, patients positive for HPV 16/18 DNA by in situ hybridization or antipeptide IgA antibodies to HPV 18 tended to have fewer Langerhans cells than those negative for HPV 16/18 DNA or IgA antibodies. Our results suggest that depletion of Langerhans cells is associated with productive HPV 16/18 infection in the cervical epithelium.

Dynamic nature and function of epidermal Langerhans cells in vivo and in vitro: a review, with emphasis on human Langerhans cells

Epidermal Langerhans cells (LC) are Birbeck granule-containing bone-marrow-derived cells, which are located mainly in the suprabasal layer of the epidermis. They can be readily identified by their strong expression of CD1a and MHC class II molecules. In addition to these 'classical' properties, an extensive phenotypic profile of normal human LC, summarized in this review, is now available. The powerful capacity of LC to activate T lymphocytes is clearly documented and, to date, LC are recognized as the prominent antigen-presenting cells of the skin immune system. They are generally believed to pick up antigens encountered in the epidermis and to migrate subsequently from the epidermis to the skin-draining lymph nodes. Upon arrival in the paracortex of lymph nodes, the antigen-laden LC transform into interdigitating cells and they present antigen to naive T lymphocytes in a MHC class II-restricted fashion; this results in the generation of antigen-specific immune responses. It has also been demonstrated that transformation of LC into interdigitating cells occurs when LC are cultured in vitro. Both in vivo and in vitro studies have indicated that properties of LC, such as phenotype, morphology and the stimulatory potential to activate T lymphocytes, are dependent on the local microenvironment in which the LC reside. The essential role of LC in the induction of contact allergic skin reactions and skin transplant rejection is well established.

Cultured human Langerhans cells process and present intact protein antigens

Epidermal Langerhans cells (LC) undergo profound phenotypic and functional alterations when cultured for 2 to 3 d. To determine whether the in vitro culture of human LC modulates their capacity to process and present intact protein antigens, we compared the ability of freshly isolated LC (fLC) and cultured LC (cLC) to stimulate in vitro T-cell proliferative responses to recall antigens. We found that human fLC and cLC were able to process and present recall antigens to primed T cells, inducing significant proliferative responses. For tetanus toxoid and Candida albicans extract, T-cell proliferative responses at 6 d to antigen-pulsed fLC were slightly greater than responses to antigen-pulsed cLC. For live influenza A virus, the T-cell responses induced by antigen-pulsed cLC were comparable or slightly greater compared with fLC. Allogeneic T-cell proliferation for both LC preparations were also comparable. The exogenous pathway of antigen processing was demonstrated by chloroquine inhibition.

CD-1 (T6), HLA-DR-expressing cells, presumably Langerhans cells, in nasal mucosa

In the skin, epidermal Langerhans cells (LC) constitute a major population of antigen-presenting cells. These cells are characterized by the expression of both CD-1 (T6) and HLA-DR on the cell membrane. We wanted to know whether similar CD-1/HLA-DR-positive cells occur in the nasal mucosa of patients with an isolated grass pollen allergy and in non-allergic controls. CD-1/HLA-DR-positive dendritic cells were found in columnar and cuboidal epithelium and the lamina propria of the nasal mucosa. These CD-1/HLA-DR-positive cells presumably correspond with LC in the skin. We also found significantly more CD-1-positive cells in nasal biopsy samples of allergic than in those of the non-allergic controls. In the allergic patients some of the CD-1-positive cells were found to be surface IgE-positive, possibly due to passive adherence of IgE to Fc receptors.

Reduced density and morphologic alteration of Ia and ADPase positive Langerhans cells after low-protein diet

This study examined the effects of low-protein diet on the population density, morphology and histochemical characteristics of Langerhans cells. Weaned at 18 days old, BALB/c mice were divided into two groups: one group received a high-protein diet (20% casein) and the other was fed an isocaloric low-protein diet (caesin 4%). After 14 days, the mice were killed and the skin of the ears was removed for investigation. Langerhans cells were visualized using ADPase and anti-Ia immunoperoxidase techniques. In protein malnourished mice, the density of ADPase and Ia-positive Langerhans cells was significantly reduced, while morphometric assessment of their cross-sectional area showed a significant reduction of total cell area, cell body area and degree of arborization. Quantitative cytophotometric analysis revealed a reduction of ADPase ectoenzyme activity and decreased concentration of membrane Ia antigen. We postulate that these changes affect Langerhans cell functions, and in turn influence the immune mechanisms in the skin.

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.

A single step centrifugation method for the enrichment of veiled cells from canine afferent lymph

Veiled cells (VC) present in the afferent lymph of dogs with chronic lymphoedema could be enriched from 6% to about 50% VC by density gradient centrifugation on 15% metrizamide or discontinuous Percoll gradients. The recovery of VC was about 40% from 0.22 +/- 0.07 X 10(6) VC/ml of lymph. The cells were strongly Ia positive and had cytoplasmic S 100 protein. They were also strongly ATP-ase positive and showed heterogeneity in acid phosphatase, peroxidase and non-specific esterase activity. Low density VC from canine afferent lymph were able to stimulate both blood and lymphatic lymphocytes in autologous mixed leukocyte reaction when present at concentration as low as 5% of cultured cells.

Ultrastructural features of Langerhans cells in clinically uninvolved skin of psoriatics

Epidermal Langerhans cells (LC) from skin of clinically normal appearance in psoriatics were studied electron microscopically and compared with LC from the skin of healthy volunteers and from those with other dermatoses. Results show that LC from psoriatics display partly distinct cytoplasmic alterations. Moreover, about half of LC investigated were partly or mainly surrounded by clearly widened intercellular spaces, such that an immediate cellular contact with neighbouring keratinocytes was correspondingly decreased. Whether such LC are functionally altered remains to be clarified.

Langerhans' cells and subtypes of human papillomavirus in cervical intraepithelial neoplasia

There is strong circumstantial evidence that human papillomavirus is a cofactor in the development of cervical neoplasia. Systemic immunosuppression has also been implicated. A study was therefore carried out examining the relation between subtypes of human papillomavirus and local immunocompetent cells in the cervix. Colposcopically directed punch biopsy specimens were taken from normal cervix and from histologically proved cervical intraepithelial neoplasia for immunohistochemical studies. Human papillomavirus genome probing was performed on the abnormal specimens. A relation was apparent between decreased Langerhans' cells and moderate to high copy numbers of human papillomavirus type 16. The reduction in Langerhans' cells was significant for human papillomavirus type 18 even at low copy numbers. Conversely, the absence of human papillomavirus was associated with increased numbers of Langerhans' cells in cervical intraepithelial neoplasia. These findings suggest that the proposed oncogenic potential of human papillomavirus type 16 and human papillomavirus type 18 in particular may be mediated by a specific effect on the afferent limb of the immune response.

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.

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.

Identification and quantification of subsets of mononuclear inflammatory cells in melanocytic and other human tumors

We used monoclonal antibodies and an indirect immunoperoxidase technique to identify mononuclear inflammatory cells associated with human tumors. The absolute number of the different types of inflammatory cells was assessed by using a point-counting technique. We studied tissues from six primary cutaneous melanomas, six metastatic melanomas, eight melanocytic nevi, 14 breast cancers, seven examples of fibrocystic disease of the breast, 11 lung cancers, and six colon cancers. Virtually all tumors were associated with substantial numbers of T lymphocytes (Leu3a-positive T helper-inducer cells predominating) and macrophages. Primary melanomas contained significantly more T lymphocytes (P less than .002), macrophages (P less than .005), and Langerhans/dendritic cells (P less than .002) than nevi or normal skin and had a higher proportion of T cells than metastatic melanomas (P less than .01). Breast cancers contained more T lymphocytes and macrophages than occur with fibrocystic disease (P less than .0001 and P less than .002, respectively) and more B lymphocytes. Cancers of the lung and colon contained moderate numbers of T lymphocytes and macrophages; however, colon cancers contained a higher proportion of B cells. Leu7-positive NK/K cells were noted in small numbers in all tumors examined.

Mononuclear cell infiltrates in bullous disease

Mononuclear cell subset-specific monoclonal antibodies, indirect immunoperoxidase labeling, and a specific quantification technique were used to determine the constitution of mononuclear cell infiltrates associated with bullous pemphigoid (BP), pemphigus vulgaris (PV), dermatitis herpetiformis (DH), and linear IgA bullous disease, as well as those in normal skin (NS) from healthy adult volunteers. Bullous pemphigoid and PV lesions contain significantly greater numbers of T lymphocytes (p less than 0.001), including both T helper/inducer and T cytotoxic/suppressor subsets, macrophages (p less than 0.002), and Langerhans cells (p less than 0.01), than NS or lesions of DH, supporting the concept that cell-mediated immunity is involved in bulla formation and autoantigen presentation in BP and PV. The infiltrates associated with DH lesions appear to reflect a different mechanism of autoantibody production and bulla formation.

Role of epidermal Langerhans cells in resistance to herpes simplex virus infection

To investigate the role of epidermal Langerhans cells (LC) in resistance to herpes simplex virus (HSV) infection, nonadherent spleen cells taken from BALB/c mice immunized with HSV were cultured with syngeneic epidermal cells (EC) and ultraviolet light-inactivated HSV antigen. After five days of culture, T cell-dependent proliferative response was determined by 3H-thymidine incorporation. Treatment of EC with anti-Iad monoclonal antibody plus complement before cultivation prevented this proliferation, which suggested that LC induced stimulation of immune T cells. When these stimulated spleen cells were transferred to intracutaneously infected nude mice, the virus titer in the skin was reduced markedly and the formation of zosteriform skin lesions was completely inhibited. On the other hand, transfer of unstimulated cells, which were cultured with HSV antigen only or with HSV antigen and EC treated with anti-Iad monoclonal antibody plus complement, resulted in delayed viral clearance and development of the lesions. These results indicate that LC are of importance as accessory cells in the control of cutaneous HSV infection. Furthermore, Lyt 1+ T cells in the stimulated population were shown to have greater protective activity than Lyt 2+ T cells.