Sadao Anan

Immunohistochemical studies in mite antigen-induced patch test sites in atopic dermatitis

The role of mite allergen in atopic dermatitis is still unclear. In this study, we investigated whether an eczematous reaction could be induced by patch testing with dust mite antigen. We succeeded in reproducing an eczematous lesion and the mite RAST-positive AD group showed a positive reaction much more than the RAST-negative group. Many mite antigen-bearing Langerhans cells, also possessing IgE molecules, were found by the use of an immuno-double labelling technique. By using immunoelectron microscopy, it was observed that the mite antigens were trapped by some macrophages, which were apposed to lymphocytes. To investigate the time-course of the reaction, the patch test reactions were read and biopsied after 1 h, 6 h, 24 h and 48 h. An eczematous reaction developed 24 h after patch testing. The mite antigen-bearing Langerhans cells were seen exclusively in the epidermis after 6 h, and mainly in the dermis after 24 h and 48 h. These results suggested that IgE-mediated contact hypersensitivity to mite antigen may develop and play an important role in AD.

House dust mite (HDM) antigen in naturally occurring lesions of atopic dermatitis (AD): The relationship between HDM antigen in the skin and HDM antigen-specific IgE antibody

To elucidate the etiological role of house dust mite (HDM) antigen in the pathogenesis of atopic dermatitis (AD), we conducted immunohistochemical studies on the localization of HDM antigen in naturally occurring lesions of AD. HDM antigens were found in the epidermis and dermis in 19 of 38 cases. All of the 19 patients had HDM antigen-specific IgE antibody, but HDM antigen was not detected in the lesions of patients without HDM antigen-specific IgE or in control skin specimens. Most HDM antigens were located on Langerhans cells (LCs) or near helper T cells. Our findings suggest that HDM antigen is the causative factor in the development of eczematous lesions of AD, and thus we hypothesized that IgE-mediated allergic contact sensitivity to HDM antigen plays an important role in the pathogenesis of AD.

High affinity IgE receptor (FcεRI) expression on eosinophils infiltrating the lesions and mite patch tested sites in atopic dermatitis

Expression of the high affinity IgE receptor (FcεRI) on eosinophils has recently been reported. This led us to evaluate FcεRI expression on eosinophils in atopic dermatitis (AD). Double immunofluorescence stainings with an anti-FcεRI monoclonal antibody (mAb) and a polyclonal antieosinophil cationic protein (ECP) antibody were performed on lesional biopsy specimens from patients with AD and from patients with bullous pemphigoid (BP) as controls. In AD and BP lesions, 77% and 70% of eosinophils expressed FcεRI, respectively. However, the intensity of FcεRI staining in AD was much stronger than in BP, suggesting upregulation of FcεRI expression on eosinophils in AD. In addition, the eosinophils infiltrating AD lesions were stained strongly with anti-CD23 mAb and anti-IgE antibody. At the sites of mite patch testing in AD, FcεRI-, CD23- and IgE-positive eosinophils were observed to the same degree as in the lesions, and a considerable number of mite antigen-bearing eosinophils were detected. FcεRI and CD23 were both upregulated on the skin-infiltrating eosinophils in AD and bound IgE molecules.

The relationship between eosinophils, OKT6-positive cells and house dust mite (HDM) antigens in naturally occurring lesions of atopic dermatitis

To determine the role of eosinophils in naturally occurring lesions of atopic dermatitis, we observed the distribution of eosinophil cationic protein (ECP) and the relationship between eosinophils, OKT6-positive cells and house dust mite (HDM) antigens. Some specimens showed many EG2-positive stains, although the accumulation of tissue eosinophils was not prominent. EG2 stains were seen not only in eosinophils but also in extracellular granules. Some macrophage-like cells of the dermis showed EG2 stains in the form of phagocytized eosinophil granules. Some EG2-positive eosinophils were in close contact with OKT6-positive cells in the epidermis and dermis. Furthermore, in three patients sensitive to house dust mite (HDM) antigen, HDM antigens invaded the skin with many EG2-positive stains. These results suggest that eosinophils play an active role in the development of eczematous lesions of atopic dermatitis.

Circulating Immune Complexes and Their Possible Relevance to Other Immunological Parameters in Guatemalan Onchocerciasis

Circulating immune complexes (CIC) were demonstrated in sera of Guatemalan patients with onchocerciasis by Raji cell radioimmunoassay. 44% of patients but none of controls had abnormally high concentrations of CIC in their sera. The increased concentrations of CIC were found more frequently in patients with lower density of microfilariae in their skin biopsies. Patients with higher concentrations of CIC appeared to have increased titers of serum antibodies to Onchocerca volvulus. A depression of both humoral immune response to tetanus toxoid and delayed hypersensitivity reaction to PPD were found in patients with onchocerciasis. CIC may be involved in modulation of the immune response in onchocerciasis.

Dermo-epidermal blister formation by linear IgA dermatosis sera in normal human skin in organ culture.

Fresh normal human skin samples were cultured at 37°C for 48 hours with sera from 3 patients with linear IgA dermatosis and 2 patients with dermatitis herpetiformis (DH). Dermo‐epidermal separation (DES) occurred in the skin samples cultured with the sera from linear IgA dermatosis patients, and linear IgA deposition was observed in the dermo‐epidermal junction zone. However, no IgA deposition or DES was observed in the skin cultured with the sera of DH patients or normal individuals.

A case of cold urticaria due to a serum factor belonging to the IGE class.

A case of cold urticaria showing a positive Prausnitz‐Küstner (P‐K) reaction was studied. The results obtained were as follows: 1) the P‐K reaction was positive, 2) skin fixation time was 21 days, 3) the P‐K reaction could be blocked by heating the serum for 2 hours at 56°C, and 4) the P‐K reaction became negative after adsorption of IgE from the serum. These data suggest that the serum factor responsible for cold urticaria in this case belongs to the IgE class. The effect of histamine liberator 48/80, histological examination of the skin and results of the estimation of serum histamine concentration by a fluorometric method all suggest that this wheal formation is due to a histamine release from mast cells in the skin.

Immunological studies of onchocerciasis in Guatemala. I. Immunoglobulin levels in Guatemalan onchocerciasis.

The serum levels of the four immunoglobulins, IgG, IgA, IgM and IgE, in Guatemalan onchocerciasis patients were determined quantitatively using a laser immunoassay system or radioimmunosorbent test.

Immunoglobulins and Their Receptors on Epidermal Langerhans Cells in Atopic Dermatitis

To elucidate the etiological role of immunoglobulin molecules on Langerhans cells (LCs) in atopic dermatitis, we conducted immunohistochemical studies on the localization of immunoglobulin G1 (IgG1), IgG2, IgG3, IgG4, IgA and IgM on epidermal LCs from 30 patients with atopic dermatitis (AD) and five non‐atopic healthy volunteers. We also investigated the types of receptors for the immunoglobulins (FcεRI, FcεRII, FcγRI, FcγRII, and FcγRIII) on epidermal LCs in the patients.

Contact hypersensitivity reaction to ovalbumin in newborn guinea pigs from maternally sensitized animals

An animal study was conducted to elucidate the role of ovalbumin (OA) in the development of eczematous lesions in intrauterine sensitized newborns. Four groups of pregnant guinea pigs were used: group A, immunized by oral administration of 1% OA in drinking water until parturition; group B, immunized by intradermal injection of OA with Freunds complete adjuvant; group C, immunized by both methods; and group D (control), not immunized. The newborn guinea pigs of each group were patch tested with 10% OA in white petrolatum. Positive reactions were seen in the newborns of groups B and C, but not in those in groups A and D. By enzyme-linked immunosorbent assay and passive cutaneous anaphylaxis, a high titre of OA-specific IgG was detected in the group B and C newborns. The number of positive patch test reactions decreased concomitantly with the decline of specific IgG. Histologically, eczematous changes were observed in the positive reaction sites. Many OA antigen-bearing Langerhans cells were found by the immuno-double labelling technique. Immuno-electron microscopic findings revealed the presence of OA antigens as well as IgG molecules on the cytoplasmic membranes of Langerhans cells. Our studies demonstrated that maternal sensitization with OA can induce an eczematous reaction in the newborns to OA patch testing under the presence of high levels of OA-specific IgG in the serum. From these findings it is suggested that IgG plays an essential role in the development of contact hypersensitivity reaction to OA.