Dynamic changes in epidermal Ia-positive cells in allergic contact sensitivity reactions in mice

Langerhans cells within the follicular epithelium and the intradermal sweat duct in equine insect hypersensitivity "Kasen"

Histopathologic and electron microscopic observations were given on Langerhans cells (LCs) within the follicular epithelium (FE) and intradermal sweat duct (ISD) of equine "Kasen". By light microscopy, LCs were present in the greatest numbers within the FE and ISD than within the epidermal layer and the normal skin, with an occasional formation of several aggregated foci. By electron microscopy, LCs within the FE and ISD widely extended their dendritic processes between the keratinocytes and contained Birbeck granules (Bgs), mitochondria, rough endoplasmic reticula and ribosomes in the cytoplasm. Numerous Type 2 LCs, with a number of Bgs and endocytosis, and Type 3 LCs, with multivesicular bodies and endosomes of various sizes, were recognized within the FE and ISD, although inactive Type 1 LCs, with a narrow and lucid cytoplasm, were rarely seen. LCs observed within the FE and ISD in the "Kasen" skin lesions might express the particular stage corresponded to recognize, intake and process the antigens which permeate them.

Maturation of dendritic cells induced by cytokines and haptens

Recently, elucidation has progressed on a crucial role played by dendritic cells (DCs) in the induction of primary antigen-specific immune reactions. Although mature DCs exhibit potent antigen presenting function, DCs are scattered in nonlymphoid organs throughout the body as immature cells that have only minimum antigen presenting function. When they are stimulated to maturate, they increase their expression of class II major histocompatibility (MHC) antigen and several co-stimulatory molecules, resulting in the augmentation of antigen presenting function. Furthermore, these maturated DCs move to the T-dependent areas of secondary lymphoid organs to sensitize naive T cells for these antigens. Therefore, it is important to understand the mechanism to induce the maturation of DCs. Recent progress in the study of DC biology depicts various factors, such as cytokines, bacterial products and haptens, which are responsible for DC maturation. In this paper, the mechanism of DC maturation induced by cytokines and chemicals is described.

Keratinocyte expression of B7-1 in transgenic mice amplifies the primary immune response to cutaneous antigens

Resting epidermal keratinocytes do not express B7-1 and other known CD28 counterligands with costimulatory activity. The absence of these costimulators on keratinocytes correlates with their ability to preferentially induce T-cell anergy instead of T-cell activation. To test the hypothesis that keratinocytes expressing a CD28 counterligand would be more effective inducers of T-cell-mediated immune responses in skin, we prepared transgenic mice in which expression of the B7-1 costimulator was targeted to basal keratinocytes by using the human K14 promoter. Keratinocytes from the K14/B7-1 transgenic line expressed high levels of surface B7-1. No spontaneous inflammatory changes were seen in transgenic skin, but epicutaneous application of contact sensitizers to these mice elicited a stronger primary ear swelling response than in controls. Sites of initial hapten application in transgenic mice also responded much more strongly to reapplication of hapten to a remote cutaneous site. Epidermal cell suspensions from transgenic mice contained normal numbers of Langerhans cells and dendritic epidermal T cells when analyzed by flow cytometry. Systemic treatment of the transgenic mice with interferon gamma induced high levels of class II major histocompatibility complex expression on keratinocytes but was not sufficient to initiate an inflammatory response. We conclude that the constitutive expression of the B7-1 molecule in vivo on a nonprofessional antigen-presenting cell is not by itself sufficient to trigger inflammatory changes, but B7-1 expression amplifies the host immune responses after exposure to nonself antigens presented by B7-1-expressing cells.

CD1a and S100 antigen expression in skin Langerhans cells in patients with breast cancer

Langerhans cells (LCs) are dendritic, antigen-presenting cells found in the epidermis. This study investigates the effect of early breast cancer on the expression of CD1a and S100 antigens by these cells. LCs were counted and expressed as cells/mm of epithelial basement membrane on biopsies from the skin overlying the tumour and from biopsies distant from the tumour. A control study was performed on normal breast skin, not adjacent to a lesion, from women with benign breast disease. The LC count of 18 patients undergoing biopsy for benign breast disease indicated a mean of 26 cells/mm [95 per cent confidence interval (CI) 23-29] and a S100/CD1a ratio of 70 per cent. In 35 cases of early breast cancer, the CD1a-positive LC count in the epidermis overlying the carcinoma (mean 26/mm; 95 per cent CI 23-29) was similar, but the count made on biopsies distant from the tumour (mean 21/mm; 95 per cent CI 19-23) was significantly smaller. The percentage ratio of S100/CD1a was 71 per cent over the carcinoma and 84 per cent in the distant biopsies. The changes were not associated with the presence of nodal metastases or the oestrogen and progesterone status of the primary tumour. The reduction in LC numbers provides a link between decreased monocyte function and the decreased skin hypersensitivity responses found in patients with breast cancer.

Langerhans cells in human allergic contact dermatitis contain varying numbers of Birbeck granules. Double staining immunohistochemistry with OKT6 and Lag antibody

Dynamic changes in human Langerhans cells (LCs) were studied with OKT6, anti-HLA-DR antibody, and Lag antibody in allergic contact dermatitis (ACD). Both T6-positive (T6+) cells and Lag-positive (Lag+) cells in the epidermis decreased in number from 0 to 48 h, but then gradually increased after day 7 of ACD. Lag+ cells after day 7 manifested a variety of staining intensities from weak to strong. It was also shown, after day 7, that some T6+ cells were Lag negative whereas all Lag+ cells were T6 positive. Flow cytometric analysis suggested that Lag-strongly-positive cells and Lag-weakly-positive cells belonged to the same population, and that the relative amount of Lag antigens in T6+ LCs gradually increased after day 7. Immunoelectron microscopy revealed that the Lag-strongly-positive cells contained numerous Lag-reactive Birbeck granules (BGs) whereas the Lag-weakly-positive cells contained fewer BGs in the cytoplasm. In some Lag-weakly-positive cells, no BGs were detected.

Cross-reactivity of murine monoclonal anti-DNA antibodies with human and murine skin: a possible pathogenetic role in skin lesions of lupus erythematosus

Anti-DNA autoantibodies are known to cross-react with a wide variety of substances including cell-surface molecules. Thus, we examined cross-reactivities of 20 murine monoclonal anti-DNA antibodies with normal human and mouse skin tissues. Hybridomas producing these monoclonal antibodies were established from non-immunized spleen cells from autoimmune MRL-lpr/lpr mice, a strain characterized by spontaneous development of SLE-like disorders including skin changes. They were selected based on their reactivity to DNA in a typical enzyme-linked immunosorbent assay, in which nine monoclonal antibodies were reactive with both double-stranded DNA and single-stranded DNA, whereas nine monoclonals were reactive only with single-stranded DNA. Even though only seven of them were observed to stain nuclei, most of the monoclonal antibodies revealed strong and distinct cross-reactivities to various components of the skin tissues including the epidermal basement membrane, keratinocytes at different locations of the epidermis, melanocytes, Langerhans cells, Thy-1+ dendritic cells in the case of murine skin, and mast cells. Our results suggest a possible role of so-called anti-DNA antibodies with high or low affinities to DNA in the pathogenesis of cutaneous lesions of lupus erythematosus.

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.

Localization of antigen on lymph node dendritic cells after exposure to the contact sensitizer fluorescein isothiocyanate. Functional and morphological studies

We have examined the cells involved in the development of contact sensitivity to FITC in CBA mice. After skin painting with antigen, the number of dendritic cells (DC) in the draining lymph nodes increased by 30 min, was maximal at 48 h, and returned to normal by 6 d. Derivation of some DC from Langerhans' cells of the skin was indicated from the presence of Birbeck granules observed in some DC isolated 24 h after skin painting. The DC acquired FITC and by 8 h there were two populations, one highly fluorescent and the other less fluorescent. The highly fluorescent cells were present between 8 h and 3 d after sensitization, and during this period the DC were potent at initiating primary proliferative responses of normal syngeneic T lymphocytes in vitro. Between days 3 and 5 the numbers of lymphocytes in the draining lymph node increased. During this period purified T lymphocytes did not express detectable levels of antigen, but enriched B cell populations expressed antigen transiently on day 1, 2, or 3 after exposure to antigen. The results showed that, during a 3-d period after exposure to antigen, DC expressed antigen and stimulated T cell proliferation. We speculate that low amounts of FITC binding selectively to veiled cells or lymph node DC in the first hours after exposure to antigen are not immunogenic but that Langerhans' cells acquire high levels of antigen, enter the nodes, and initiate immune responses.

Functional analysis of Ia antigen-bearing keratinocytes: mixed skin lymphocyte culture between Ia antigen-bearing Pam 212 cells and allogeneic and syngeneic splenic T cells

Keratinocytes express Ia antigens in various skin disorders, although the biological role of these Ia antigen-bearing (Ia+) keratinocytes remains unclear. We induced Ia antigens on Pam 212 murine keratinocyte cell line by interferon-gamma(IFN-gamma) and using these cells, we performed the mixed skin lymphocyte culture with syngeneic BALB/c or allogeneic C3H/He splenic T cells. Unexpectedly, Pam 212 cells were found to stimulate both syngeneic and allogeneic T cells irrespective of IFN-gamma treatment. However, both syngeneic and allogeneic T cells cultured with IFN-gamma-treated Pam 212 cells incorporated [3H]thymidine much more actively than those cultured with IFN-gamma-untreated Pam 212 cells. This stimulation was not inhibited by monoclonal anti-I-Ad antibody. Analysis of the responding T cells demonstrated that the syngeneic T-cell stimulation by IFN-gamma-treated Pam 212 cells occurred in both purified Lyt 1-T cells and Lyt 2- T cells. Furthermore, we found that the T cells cultured with the IFN-gamma-treated cells were composed of two morphologically different types of cells. Determination of their surface phenotype showed that the small cell population consisted of 57% Thy-1+, 23% Lyt-1+, 6% Lyt-2+, and 9% asialo-GM1+ cells, while the large cells consisted of 53% Thy-1+, 15% Lyt-1+, 9% Lyt-2+, and 24% asialo-GM1+ cells. These findings suggest that IFN-gamma-treated Pam 212 cells could stimulate more than one kind of splenic T cell populations.

Effects of ultraviolet irradiation on surface marker expression by epidermal immunocompetent cells and contact sensitization to dinitrofluorobenzene in mice

We studied the effects of ultraviolet (UV) irradiation on murine epidermal Ia-positive Langerhans cells (Ia + LC) and Thy-I-positive dendritic epidermal cells (Thy-I + dEC). We also studied contact hypersensitivity to dinitrofluorobenzene (DNFB) introduced through UV-treated epidermis. C3H/HeN mice were exposed to UVB or 8-methoxypsoralen plus UVA (PUVA). UVB and PUVA treatment led to a dramatic reduction in surface marker expression of both Ia + LC and Thy-I + dEC. High-dose UVB irradiation (360 J/m2) interfered with contact hypersensitivity to DNFB; the density of Ia + LC may thus be related to the sensitizing potential. In contrast, low-dose UVB (120 J/m2) and PUVA treatment had little effect on contact hypersensitivity despite a marked reduction in Ia + LC. The density of Thy-I + dEC appeared not to be associated with contact hypersensitivity. These results suggest that there may be a Langerhans cell density-independent mechanism for the induction of contact hypersensitivity.

Cellular kinetics of delayed hypersensitivity test reactions to topical glucocorticosteroids

The phenotypes of the infiltrating cells in 13 patients with delayed hypersensitivity to topical glucocorticosteroids (GCS) were studied from sequential biopsies of positive epicutaneous test reactions by using the avidin-biotin-complex (ABC) technique. Monoclonal antibodies were used to identify the cells with the following phenotypes: T3, T4/T4a, T6, T8, T9, T11, M1, Ia1 (HLA-DR), interleukin-2 receptor/T26a, and dendritic reticular cell. The cellular kinetics of GCS hypersensitivity reactions were compared with delayed hypersensitivity reactions caused by allergens not related to GCS. In both GCS and non-GCS reactions the epidermal dendritic T6+ cells were more numerous than dendritic Ia1+ cells. There was a decrease in the number of both cell types during these reactions; in GCS reactions the decrease in the number of T6+ cells was seen later than in non-GCS reactions. Ia1+ keratinocytes were seen at sites near dermal infiltrates. Compared with the non-GCS delayed hypersensitivity reaction, there were fewer pan T (T11+/T3+) in the GCS reaction. The relative numbers of M1+ monocytes and the T4/T8 ratio were substantially lower in the latter; these findings can be explained as a GCS effect which modulates the delayed type hypersensitivity reaction.

Changes in expression of Ia, Thy-1, and Ly-5 antigens in epidermal cells during delayed contact sensitivity reactions in mice: flow cytometric analysis

Ia antigen-bearing (Ia+) Langerhans cells have attained an important position as immunocompetent cells in the epidermis. Recently there have been successive reports on other new possible candidates for immunocompetent cells in the epidermis, i.e., Ia+ keratinocytes and dendritic Thy-1 antigen-bearing (Thy-1+) epidermal cells which also express Ly-5 antigen and asialo-GM1. Based on our previous findings that in allergic contact sensitivity reactions, keratinocytes express Ia antigen 3-9 days postchallenge, in this report, we have attempted to define more clearly the dynamic changes of Ia+ keratinocytes and dendritic Thy-1+ epidermal cells by enumeration of the precise percentages of Ia+, Thy-1+, and Ly-5 antigen-bearing (Ly-5+) cells in epidermal cells at various times of the challenge phase in allergic contact sensitivity reactions by use of a fluorescence-activated cell sorter. By 24 h postchallenge, the percentages of Ia+, Thy-1+, and Ly-5+ cells showed hardly any change. There were approximately 2% Ia+ cells, 50% Thy-1+ cells which consist of 2 populations (i.e., 45% weakly Thy-1 antigen-positive cells and 4% strongly Thy-1 antigen-positive cells), and 3.5% Ly-5+ cells. From 48 h postchallenge, however, the percentage of Ia+ cells and that of Thy-1+ cells began to increase and reached a plateau, with approximately 20% Ia+ cells and 70% Thy-1+ cells, respectively, at 120 h postchallenge. The change of the percentages of Ly-5+ cells appears to correspond to that of strongly Thy-1 antigen-positive cells. Only at 48 h postchallenge, Ly-5+ cells and strongly Thy-1 antigen-positive cells showed a small increase in number, comprising approximately 10% of the epidermal cells. These data suggest that among Thy-1+ epidermal cells, strongly Thy-1 antigen-positive cells correspond to dendritic Thy-1+ epidermal cells, and in contact sensitivity reactions in mice, dendritic Thy-1+ epidermal cells show only a minor dynamic change in contrast to Ia+ cells, in which more than 15% of keratinocytes express Ia antigen from 48 h postchallenge.