Local immune response in basal cell carcinoma: characterization by transmission electron microscopy and monoclonal anti-T6 antibody

Langerhans Cells, Inflammation Markers and Human Papillomavirus Infections in Benign and Malignant Epithelial Tumors from Transplant Recipients

Organ transplant recipients frequently develop warts which progress toward premalignant or malignant lesions after a rather long grafting period. The local immune responses of such lesions (warts, condyloma acuminata, actinic keratoses, Bowen, basal and squamous cell carcinomas) was studied in 32 frozen skin specimens taken from 15 male transplant recipients and compared to similar lesions from the normal population. We studied the expression of T cell subsets, Langerhans cell phenotype, HLA class 1 (beta 2-microglobulin), HLA class 2 (DR antigen), and intercellular adhesion molecule 1 (ICAM 1). The presence of HPV infection was also considered, using in situ hybridization with biotinylated probes in order to examine the correlation with immunological markers. In the dermis, the lesions from grafted patients showed a moderate to intense inflammatory reaction of HLA-DR-positive cells. Most of these cells were CD4+ and CD8+ without any predominance of a single T cell subset. In the epidermis, most lesions were characterized by a reduced number of CD1-positive cells; this was concomitant with a decrease or a loss of beta 2-microglobulin expression by epithelial cells. HLA-DR antigen was not expressed by keratinocytes or tumoral cells in any specimen; ICAM 1 antigen was observed in a few cases. The expression of these markers was similarly modified with or without the presence of HPV DNA. Conversely, most lesions from non-immunocompromised patients, except warts, showed intense inflammatory reactions, with a predominance of CD4-positive cells and large foci of ICAM 1-positive cells. Expression of activation markers by keratinocytes occurred mainly in condylomas and squamous cell carcinomas. In the normal population, HPV infection was only detected in papilloma lesions. These data indicate, in lesions from grafted patients, a lack of effective immune response with partial inhibition of activation markers expressed by keratinocytes. It is conceivable that immunosuppressive treatment with solar exposure may also be responsible for the local immune deficiency and thus for the conversion of benign warts toward malignant lesions in grafted patients.

Arsenic carcinogenesis in the skin

Chronic arsenic poisoning is a world public health issue. Long-term exposure to inorganic arsenic (As) from drinking water has been documented to induce cancers in lung, urinary bladder, kidney, liver and skin in a dose-response relationship. Oxidative stress, chromosomal abnormality and altered growth factors are possible modes of action in arsenic carcinogenesis. Arsenic tends to accumulate in the skin. Skin hyperpigmentation and hyperkeratosis have long been known to be the hallmark signs of chronic As exposure. There are significant associations between these dermatological lesions and risk of skin cancer. The most common arsenic-induced skin cancers are Bowen's disease (carcinoma in situ), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Arsenic-induced Bowen's disease (As-BD) is able to transform into invasive BCC and SCC. Individuals with As-BD are considered for more aggressive cancer screening in the lung and urinary bladder. As-BD provides an excellent model for studying the early stages of chemical carcinogenesis in human beings. Arsenic exposure is associated with G2/M cell cycle arrest and DNA aneuploidy in both cultured keratinocytes and As-BD lesions. These cellular abnormalities relate to the p53 dysfunction induced by arsenic. The characteristic clinical figures of arsenic-induced skin cancer are: (i) occurrence on sun-protected areas of the body; (ii) multiple and recrudescent lesions. Both As and UVB are able to induce skin cancer. Arsenic treatment enhances the cytotoxicity, mutagenicity and clastogenicity of UV in mammalian cells. Both As and UVB induce apoptosis in keratinocytes by caspase-9 and caspase-8 signaling, respectively. Combined UVB and As treatments resulted in the antiproliferative and proapoptotic effects by stimulating both caspase pathways in the keratinocytes. UVB irradiation inhibited mutant p53 and ki-67 expression, as well as increased in the number of apoptotic cells in As-BD lesions which resulted in an inhibitory effect on proliferation. As-UVB interaction provides a reasonable explanation for the rare occurrences of arsenical cancer in the sun-exposed skin. The multiple and recurrent skin lesions are associated with cellular immune dysfunction in chronic arsenism. A decrease in peripheral CD4+ cells was noticed in the inhabitants of arsenic exposure areas. There was a decrease in the number of Langerhans cells in As-BD lesion which results in an impaired immune function on the lesional sites. Since CD4+ cells are the target cell affected by As, the interaction between CD4+ cells and epidermal keratinocytes under As affection might be closely linked to the pathogenesis of multiple occurrence of arsenic-induced skin cancer. In this review, we provide and discuss the pathomechanisms of arsenic skin cancer and the relationship to its characteristic figures. Such information is critical for understanding the molecular mechanism for arsenic carcinogenesis in other internal organs.

Liposome-mediated gene transfer into human basal cell carcinoma

Direct intralesional injection of DNA encoding interferon-alpha2 (IFN-alpha2) was used in an effort to sustain local protein delivery for the treatment of human basal cell carcinoma (BCC). A novel model to study this malignancy was established by transplantation of human BCC tissue on to immunodeficient mice with a relatively high rate of engraftment and stable phenotype for superficial BCC (20 of 25; 80%). Gene transfer was significantly increased by using DNA liposome complexes (lipoplexes). Recombinant gene expression was detected predominantly in the epidermis and, to a lesser extent, in the dermis. Gene transfer of IFN-alpha2 using this method resulted in sustained production of IFN-alpha2 protein and increased expression of a known IFN-inducible gene, the class II major histocompatibility (MHC) antigen, and induced BCC regression, presumably through a non-immune mechanism. Intralesional injection of DNA lipoplexes encoding IFN-alpha protein may therefore be applicable to the treatment of cutaneous BCC.

Lymphoepithelioma-like carcinoma of the skin

Lymphoepithelioma-like carcinoma of the skin is a rare tumor with a microscopic resemblance to lymphoepitheliomatous tumors of the nasopharynx. A 62-year-old woman exhibited such a tumor on the nose together with regional lymph node metastases. Histologically, irregular islands of atypical epithelial cells unconnected to the overlying epidermis were surrounded by or mixed with numerous lymphocytes in the primary tumor. No squamous or glandular differentiation was present. Metastases to the submandibular lymph nodes appeared as glassy squamous cells that resembled trichilemmal keratinization. Staining of the tumor tissues with S-100 protein antibody revealed the presence of numerous short dendritic cells in clusters of epithelial cells. Total resection and adjunctive radiotherapy have led to a 6-year period free of recurrence. This is the second case report of this condition in Japan.

Quantitative and 3-dimensional analysis of Langerhans cells in basal cell carcinoma. A comparative study using light microscopy and confocal laser scanning microscopy

We have analysed Langerhans cells (LCs) in basal cell carcinoma (BCC) and in healthy skin in 15 patients, using three different techniques: light microscopic examination of horizontal sheets, and of 6-micron-thick vertical skin sections, and confocal laser scanning microscopy (CLSM) of 25-micron-thick vertical sections. The use of CLSM enables both a quantitative and a three-dimensional (3-D) analysis of the cells in the same tissue volume. A statistically significant reduction in the relative volume of epidermal CD1a reactivity confined to tumour areas was found with CLSM. This difference was confirmed when the number of LCs in horizontal sheets were counted. In contrast, no significant reduction in epidermal CD1a+ cells was found in thin vertical sections. This is probably due to the smaller tissue sample examined, and to variations in the number of CD1a+ cells, with less cells directly overlying the tumour nests. The ratio of CD1a-expressing cells in the epidermis/dermis was significantly reduced in BCCs, compared with healthy looking skin. Few LCs were observed in tumour nests, but they were numerous in the surrounding stroma of the dermis. Three-dimensional reconstructions of CD1a+ cells in BCC revealed striking morphological changes; they had a reduced number of dendrites, and these were often short and had few branches. The results demonstrate that CLSM is a suitable technique for quantitative and morphological analysis of CD1a-expressing cells in the skin. We suggest that the alterations in LC numbers, distribution and morphology in BCC most probably are secondary to changes in the local environment.

Regression in basal cell carcinoma: an immunohistochemical analysis

Spontaneous regression of some cutaneous tumours is well recognized, and is thought to result from an immunological response to the tumour. Regression has previously been noted in basal cell carcinomas, but no studies defining the role of the immune response in the regression of this malignancy have been performed. We have examined 45 primary basal cell carcinomas (BCCs) (20 nodular, 25 superficial) and identified the cellular phenotypes and activation states of the cells infiltrating primary regressing and non-regressing BCCs, by immunocytochemistry. We have found a significantly increased number of CD3+ and CD4+ T cells infiltrating regressing compared with non-regressing tumours, and the expression of interleukin-2 receptor (an early activation marker for T cells) was also increased. There were no significant differences in class II major histocompatibility complex (MHC), CD1, or macrophage antigen expression in these groups. These findings suggest that activated CD4+ cytokine-secreting cells are important in the regression of BCCs.

Basal cell carcinoma of the eyelid and periocular skin

Basal cell carcinoma is the most common human malignancy. This locally invasive tumor rarely metastasizes, but can cause considerable morbidity when on the eyelids and periocular skin. The successful management of BCC requires an awareness of its broad clinical spectrum and knowledge of the risk factors associated with therapeutic failure. The optimal therapy for basal cell carcinoma is controversial. Treatment strategy is formulated on an individual basis, taking into account tumor size, anatomic location, and growth pattern. The immune status and life expectancy of the patient also must be considered. While complete eradication of the tumor is desirable, this can be challenging since basal cell carcinomas often extend beyond their apparent clinical margins. Since prevention is preferable to treatment, the public needs to be informed that the incidence of periocular skin cancers can be reduced with the longterm use of sunscreens, sunglasses, and hats with brims.

Mitotic Langerhans cell as a possible sign of activation in ichthyosis

The fine structure of Langerhans cells (LC) in four rare types of ichthyosis, namely recessive ichthyosis congenita type II, III and IV and ichthyosis hystrix Curth-Macklin was examined. Signs of LC activation were observed in eight of 21 patients. In IC type IV, the rare occurrence of a mitotic LC was observed. It is possible that LCs are secondarily activated in keratinization disorders.

Electron-microscopic observation of a human epidermal Langerhans cell in mitosis

Langerhans cells are dendritic cells of the epidermis originating from bone marrow precursors which may exceptionally undergo mitosis within the skin. We report herein an electron-microscopic observation of a dividing LC within a seemingly hyperproliferative human epidermis. This observation further underlines the self-reproducing capacity of LC in situ and suggests that LC may respond to the same mitogenic stimuli as keratinocytes.

Density and morphology of Langerhans cells in basal cell carcinomas of the face and trunk

We investigated the density and morphology of Langerhans cells in epidermal sheets of basal cell carcinomas in chronically sun-exposed skin (face) and less exposed skin (trunk) of 65 patients. Langerhans cells in perilesional and control skin at the same anatomical sites as the tumours were also examined. Two markers (ATPase and OKT6) were used in a parallel fashion to identify Langerhans cells. The density of the cells was reduced, and their morphology was changed in epidermis overlying tumours of both the face and trunk. These alterations were confined to tumour areas, as Langerhans cells in perilesional skin were normal when compared with control skin at both anatomical sites. Results with both markers were the same.

Biology of basal cell carcinoma (Part II)

Host-tumor relationships involve several factors that can enhance or suppress neoplastic growth. This second part of a review of basal cell carcinoma biology examines the role that hormones, cytokines, local and systemic immunity, congenital and genetic syndromes, and environmental factors play in the development of this neoplasm. Theories of etiology and pathogenesis are discussed, and transplantation and cell culture techniques used to study this cancer are explored. Valuable second-line therapies for treatment of multiple tumors are reviewed, and important areas of present and future research are emphasized.

Activation and inducer subset phenotype of the lymphocytic infiltrate around epidermally derived tumors

An in situ analysis of the mononuclear cell infiltrate found in association with a range of benign, premalignant, and malignant epidermal tumors is described. The predominant cell phenotype was that of the recently described immunoregulatory helper/inducer T lymphocyte. A large number of lymphocytes expressed antigens associated with cellular activation, suggesting an ongoing immunologic response by the host against the tumor, although evidence of in situ proliferation of these cells was lacking. These findings suggest that the infiltrate found in association with cutaneous tumors does not represent passive accumulation of lymphocytes from the circulation but rather an active antitumor response.

Constitutive absence and interferon-gamma-induced expression of adhesion molecules in basal cell carcinoma

Adhesion of lymphocytes to target cells via certain cell surface molecules is important in cytotoxic T lymphocyte-mediated immune reactions. The binding of lymphocyte function-associated (LFA) antigens 1 and 2, with their respective ligands, intercellular adhesion molecule-1 (ICAM-1) and LFA-3, which are expressed on the surface of nonlymphoid cells, has been shown to be critical for lymphocyte adhesion. To determine whether basal cell carcinomas (BCCs) can escape immunodetection as a result of the inability of cytotoxic T lymphocytes to bind tumor cells, the expression of adhesion molecules on numerous BCCs, before and after exposure to interferon-gamma (IFN-gamma), was examined. Ninety-three percent of 30 freshly excised invasive BCCs did not express ICAM-1 and 73% of 11 BCCs did not express LFA-3. However, the normal-appearing basal keratinocytes in epidermis overlying nests of BCC, did express ICAM-1, particularly when a marked LFA-1+ and LFA-2+ dermal lymphocytic infiltrate was present. After BCC tissue was incubated in vitro with IFN-gamma the expression of ICAM-1 was induced on 85% of tumors studied. Thus tumor cells did not possess an absolute inability to express adhesion molecules; rather the constitutive absence of such molecules may be due to insufficient in vivo cytokine levels necessary to induce expression or a barrier preventing cytokines from reaching and interacting with tumor cells. We conclude that the absence of ICAM-1 and LFA-3 adhesion molecules is a mechanism by which BCCs can avoid immunosurveillance.

Occurrence of Langerhans cells and expression of class II antigens on keratinocytes in malignant and benign epithelial tumors of the skin: an immunohistopathologic study with monoclonal antibodies

We used an avidin-biotin complex immunoperoxidase technique with various monoclonal antibodies to determine Langerhans cell densities, class II antigen expression on keratinocytes, and phenotypes of other infiltrating cells in several malignant and benign epithelial tumors of the skin. Our observations indicate (1) there are few Langerhans cells in nests of basal cell carcinoma and squamous cell carcinoma; (2) there are increased Langerhans cell densities in seborrheic keratoses, verrucous epidermal nevus, and Bowen's disease; (3) there is an expression of class II molecules on the keratinocytes and cancer cells of basal cell carcinoma, squamous cell carcinoma, Bowen's disease, seborrheic keratosis, and verrucous epidermal nevus; and (4) there is a netlike staining of the keratinocyte surface with OKM5 in the epidermal lesion of seborrheic keratosis, verrucous epidermal nevus, and Bowen's disease, as well as in the epidermis adjacent to the basal cell carcinoma and squamous cell carcinoma nests.

Mitotic activities of normal epidermal Langerhans cells

We have previously reported a sequence of events which occurs during the recovery phase of the murine epidermal Langerhans cells (ELCs) after ultraviolet-B irradiation. We found that an ATPase-positive round cell divides, dendrites are gradually formed, and paired dendritic cells are eventually separated as the post-irradiation time elapses. We wondered if a series of events similar to this might occur in the normal murine epidermis without irradiation. In this study, we could identify exactly the same phases of the ELC mitotic cycle in normal mouse ear skin.

Alterations in Langerhans cells during growth of transplantable murine tumors

To investigate the response of Langerhans cells to tumor growth, we examined the appearance and number of ATPase+ and Ia+ dendritic cells in the epidermis covering subcutaneous tumors. Mice were injected with cells from syngeneic UVB- and PUVA-induced tumors and a melanoma, and the overlying skin was examined at various times during progressive tumor growth. An increase in the number of ATPase+ and Ia+ dendritic cells was observed in skin over all three tumor types. Morphologic alterations in the cells were also noted, including a decrease in dendricity. These changes were apparent only in skin directly over growing tumor masses; contralateral and perilesional skin was unaffected. Injection of nontumorigenic cells and implantation of silicon did not induce changes in Langerhans cells. Regression of highly antigenic tumor cells and tumor regression in immunized mice were not accompanied by detectable alterations in Langerhans cells, whereas changes in Langerhans cells were apparent during tumor growth in nude mice. These results demonstrate that changes in the number and morphology of Langerhans cells occur in response to tumor growth but that the changes are not dependent on immunologic or inflammatory responses.

Quantitation of S100 protein-positive cells in inflamed and non-inflamed keratoacanthoma and squamous cell carcinoma

Langerhans cells (LC) were identified and quantitated in non-inflamed keratoacanthoma (KA), inflamed KA, non-inflamed squamous cell carcinoma (SCC), and inflamed SCC, by their content of S100 protein. The number of LCs per high-power field was markedly increased in inflamed KA when compared to the other groups. Using similar methods on frozen sections, the expression of HLA-DR was identified on keratinocytes in KA in areas of inflammation but not in other lesions under study. We hypothesize that increased numbers of LCs in inflamed KA are part of the process which results in tumor regression.

Epidermal Langerhans cells undergo mitosis during the early recovery phase after ultraviolet-B irradiation

We studied the recovery phase of immune response-associated (Ia)-positive or ATPase-positive epidermal Langerhans cells (ELCs) after ultraviolet B (UVB)-induced depletion by using mouse ear epidermal sheets. An area 3 mm in diameter was irradiated with 300 nm UVB light (40 mJ/cm2). A time sequence study was carried out to 56 days. During this period the Ia-positive ELC population increased stepwise, i.e., first a rapid increase between day 7 and day 14, which we called the early recovery phase, and next a gradual increase between day 42 and day 56, which we called the late recovery phase. During the early recovery phase, we found polymorphous ELCs in the irradiated area which were giant or normal in size, dendritic or round in shape, and single or paired in distribution. Electron microscopy revealed some of round and some of paired ATPase-positive ELCs to be in metaphase or telophase of mitotic division. Within the entire observation period of our study, there was no evidence suggesting migration of ELCs from hair follicles or from the nonirradiated epidermis. These findings indicated that mitosis of ELCs contribute to their repopulation during the early recovery phase.

Expression of human lymphocyte antigen (HLA)-DR on tumor cells in basal cell carcinoma

Immunohistologic studies of eight patients with basal cell carcinoma were undertaken using a series of monoclonal antibodies. In all of the patients, the majority of dermal infiltrates reacted with OKT3 and OKIa1 (HLA-DR), with a slight predominance of OKT4+ helper/inducer T cells (the mean OKT4/OKT8 ratio was 1.8). Both OKT4+ and OKT8+ cells were seen infiltrating the tumor masses. In addition, in five cases, human lymphocyte antigen (HLA)-DR was demonstrated on some tumor cells close to a vast number of HLA-DR+ infiltrates surrounding the carcinoma, but not on epidermal keratinocytes and tumor cells devoid of the HLA-DR+ infiltrates. A considerable number of OKT6+ dendritic cells were also observed surrounding the carcinoma. Staining with OKB7 and OKM1 revealed negligible reactive cells, and virtually none of the dermal infiltrates reacted with Leu-7 (HNK-1). These findings suggest that in addition to varied immunologically competent cells, expression of HLA-DR antigen on tumor cells may participate in a cellular immune reaction, a defense mechanism against tumor cell proliferation in basal cell carcinoma.

Immunohistologic studies of squamous cell carcinoma: possible participation of Leu-7+ (natural killer) cells as antitumor effector cells

Immunohistologic studies of 8 patients with squamous cell carcinoma (SCC) were undertaken using a series of monoclonal antibodies. In all of the patients, over 70% of the dermal infiltrates reacted with OKT3 and OKIal (HLA-DR), with a slight predominance of the OKT8+ suppressor/cytotoxic T subset (the mean OKT4/OKT8 ratio was 0.85). Both OKT4+ and OKT8+ subsets could be seen in contact with individual cancer cells. The percentage of OKB7+ (B) cells was less than 29% of the dermal infiltrates. Some Leu-7+ cells (less than 9% of the infiltrates) were seen in close association with individual cancer cells and none of these cells was present apart from the cancer cells. Few OKT6+ cells were observed in the papillary dermis and these had no relation to cancer cells. In the epidermis, OKT6+ dendritic cells remained within normal proportions. Staining with OKM1 revealed sporadic reactive cells. These results strongly suggest that besides T and B lymphocytes, Leu-7+ (natural killer) cells participate in a significant defense mechanism against SCC proliferation.

Langerhans cell density in epithelial skin tumors correlates with epithelial differentiation but not with the peritumoral infiltrate

We investigated the intraepithelial density of Langerhans cells in 17 epithelial skin tumors by immunohistologic and morphometric methods. There was a significant difference between seborrheic keratosis (Langerhans cell density 431 +/- 31/mm2; normal epidermis: 378 +/- 20/mm2), basal cell carcinoma (28 +/- 6/mm2), and squamous cell carcinoma (100 +/- 21/mm2). No correlation was found between the Langerhans cell density and the number of intraepithelial T lymphocytes or the extent of the peritumoral inflammatory infiltrate. A significant inverse correlation was demonstrated between mean nuclear area of the epithelial tissue and the Langerhans cell density (r = -0.7; p less than 0.05). These data indicate that the number of Langerhans cells does not influence the extent of the antitumoral immune response. The correlation with the level of epithelial differentiation may be due to different homing conditions.

The biology of basal cell carcinomas--a revisit and recent developments

This paper will review some of the present information on the biology of basal cell carcinoma. Recent developments include a better understanding of the basement membrane components surrounding the tumor nodules, as well as identifying the most actively dividing cells in solid basal cell carcinoma by autoradiographic techniques. The implications of a recently developed animal model will also be discussed.

Advances in the immunobiology of the skin. Implications for cutaneous malignancies

Recent advances in cutaneous immunobiology have led to the realization that skin is an important and unique immunologic organ. Studies on the immunobiology of skin cancers induced by ultraviolet radiation indicate that immune mechanisms can play a crucial role in the development of cutaneous tumors. This paper summarizes the evidence linking skin and the immune system and discusses current hypotheses concerning the mechanisms by which UV radiation interferes with cutaneous immunity. The significance of these findings for cutaneous carcinogenesis is discussed.

Quantitative analysis of T6-positive Langerhans cells in human skin cancers

Epidermal Langerhans cells (LC) are required for antigen-presentation and for stimulating antigen-specific T cell activation. Similar functions may be important in the immune response to malignant skin tumours. Monoclonal anti-T6 antibody was used to examine LC population in basal and squamous cell carcinomas. Positive control labeling was performed with monoclonal anti-HLA-DR antibody. The number of T6-positive LC per mm2 of section was significantly decreased (p less than 0.01) in the tumour group in comparison with a sex and age-matched control group. The number of sun-exposed and covered regions was taken into consideration in each respective group. Within the tumours, LC were found more frequently in the tumour periphery and in most differentiated tumour areas (horn pearls) than in the rest of the tumour mass. T6-positive LC were rarely found in the dermis. Moreover, LC exhibited morphological changes in specimens from tumours. Staining with anti-HLA-DR antibody revealed less numerous positive cells within tumour nests than labeling with OKT6. A relationship between T6-positive LC quantities and extent of HLA-DR-positive infiltrates around tumours could not be established. These results suggest that immunological surveillance of neoantigen-bearing tumour cells may be impaired in skin cancer. A reason for the reduced LC number may be an altered microenvironment in tumour tissue.

Langerhans cells in verruciform xanthomas: an immunoperoxidase study of 10 oral cases

Ten oral verruciform xanthomas were studied using an immunoperoxidase stain for S-100 protein. All cases exhibited positively stained dendritic cells among the mononuclear inflammatory cell infiltrate at the base of the lesions and to a lesser extent among the "foam cells". The foam cells were, however, negative for S-100 staining. We suggest that, based on these findings, verruciform xanthomas belong to a new category of "non-X histiocytoses" in which the presence of Langerhans cells suggests an immunologic pathogenesis.

Reduced epidermal Langerhans cell densities in patients with pulmonary malignancies do not correlate with anergy or nutritional status

Epidermal Langerhans cell (ELC) densities are markedly reduced in a number of clinical situations including anergic sarcoidosis patients. To help determine whether this reduction is related to the anergic or nutritional status of the patient, we examined the non-sun-exposed epidermis of 23 hospitalized patients with various malignancies (MP), 10 hospitalized control (HC) patients without malignancy, and 24 biopsies from historical control (HIC) patients. There was no significant difference in the density of HLA-DR+ ELC among HC, HIC, or patients with nonpulmonary malignancy (primary or metastatic). Six patients with pulmonary malignancy had significantly fewer HLA-DR+ and OKT6+ epidermal cells. The reason ELC densities are reduced specifically in pulmonary malignancies remains under study.

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.

Comparison of S-100 and OKT6 antisera in human skin

The monoclonal antibody OKT6 and antisera against S-100 protein have both been advocated as immunologic markers of Langerhans cells in the skin. S-100 antiserum has an advantage in its ability to stain Langerhans cells in paraffin tissues. In order to evaluate whether these antibodies stain equivalent numbers of Langerhans cells in skin, we compared the staining patterns of S-100 antiserum and OKT6 antibody on biopsy specimens from 40 patients with leprosy using immunoperoxidase techniques. Utilizing OKT6 antibody, greater numbers of positive Langerhans cells were found in the epidermis in tuberculoid leprosy, reversal reaction, and erythema nodosum leprosum than in lepromatous leprosy. However, these differences were not observed with the S-100 antiserum and, overall, fewer cells were found as compared with the OKT6 antibody. In the dermis both antibodies stained "dendritic cells" that were found encircling granulomas in tuberculoid leprosy and reversal reaction. Staining in lepromatous leprosy granulomas, in contrast to the epidermal staining pattern, revealed rare OKT6-positive cells, while S-100 cells were numerous and were more diffusely distributed throughout the granuloma. Our results indicate that antiserum to S-100 protein and OKT6 antibody stain morphologically similar cells (dendritic cells), but do not provide comparable results concerning distribution and frequency of these cells.

Biology of Langerhans cells: analysis by experiments to deplete Langerhans cells from human skin

In vivo studies have demonstrated that various treatments of skin, e.g., UV irradiation, topical corticosteroids, and tape-stripping, will temporarily deplete the epidermis of Langerhans cells (LC). Whether this loss represents simply a loss of cell surface markers unique to LC, or actual depletion of cells, is unknown. By design, normal human skin transplanted to the congenitally athymic (nude) mouse is a system devoid of circulating precursors for human LC. Because LC have been shown to be of bone marrow origin, any depletion of these cells in this system should be permanent. Treatments to deplete LC from human skin grafts on nude mice after grafting included: (a) large doses of UV radiation (400 mJ/cm2 every 48 h, X 3), (b) potent high-dose topical corticosteroids (2.5 mg betamethasone valerate/cm2 every day, X 5), (c) tape-stripping (X 20). Treatments before grafting included: (a) treating donor skin with 900 R of gamma irradiation, (b) complement fixing monoclonal antibody to Ia-like antigens of LC, followed by fresh complement, (c) monoclonal antibody conjugated to toxins. Quantitation of the number of LC was analyzed on control and treated epidermal sheets using immunodiagnostic reagents, anti-HLA-DR, and surface ectoenzymes , ATPase. Results show that both UV irradiation and topical corticosteroids reduce the number of LC by these analyses. However, within 3 weeks, recovery to pretreatment levels has occurred. X-irradiation and tape-stripping were without effect. Despite evidence that the monoclonal antibody, complement, and toxic systems were delivered to the LC within the epidermis, there is no evidence that these treatments resulted in a decrease in LC. It appears that LC are currently either long-lived or replaced locally from a proliferative pool and that certain cell membrane determinants of human LC are somewhat differentially sensitive to UV radiation and corticosteroids.

The effect of aging and chronic sun exposure on human Langerhans cell populations

ATPase histochemistry was used to examine Langerhans cell (LC) populations in the skin of young persons with no evidence of solar damage and older adults with chronic actinically damaged skin. The number of LC was significantly decreased in the older age group. Significantly fewer LC were observed in exposed vs covered skin in the older individuals; no such disparity was noted in the younger subjects. Morphologic alterations in ATPase-positive cells were noted in some specimens, most of which were taken from the exposed skin of elderly persons. The results suggest an independent, although possibly additive, quantitative and qualitative influence of aging and chronic sun exposure on the LC population. Decreased numbers of LC in the sun-damaged skin of elderly individuals may play a critical permissive role in the development of cutaneous carcinoma.