Langerhans cell- and T-lymphocyte functions in patients with atopic dermatitis with disseminated cutaneous herpes simplex virus infection

Growth of herpes simplex type 1 on skin explants of atopic eczema

In a novel approach to looking at why some children with atopic eczema are susceptible to cutaneous herpes simplex virus (HSV) infections, this study evaluates the hypothesis that HSV replicates more easily on eczematous than normal skin. Growth of HSV on eczematous skin explants was compared with growth on explants from three control groups (psoriasis, Darier's disease and normal skin) over a 2-day period. Growth of HSV was significantly less on normal skin than in atopic eczema, psoriasis and Darier's disease. Virus replicated more quickly, and grew to higher titre within 24h, in eczematous and psoriatic explants than in normal skin. A defect in skin barrier function and host defence factors including local cytokine secretion are discussed as possible mechanisms in causing the increased susceptibility of children with atopic eczema to HSV infection.

Atopic dermatitis--messengers, second messengers and cytokines

Atopic dermatitis (AD) shows many complex and interacting abnormalities of pharmacology, immunology and cellular control. Recent research in atopy has concentrated on abnormalities of cytokine production by T-helper cells. It is possible that cytokine imbalance causes many of the pharmacological and immunological changes seen in the disease. However, studies of second messenger control of cytokine release show that different second messenger signals may relate to the release and activation of particular cytokines. This review summarizes these findings and discusses how the second messenger defects reported in AD may relate to the abnormal cytokine profiles and the pharmacological abnormalities seen in the condition.

A T-helper cell epitope overlaps a major B-cell epitope in human papillomavirus type 18 E2 protein

Cultivated CD4+ T-helper cells from two patients with cervical adenocarcinoma showed responses to a peptide EKTGILTVTYHSETQRTK derived from an E2 protein of human papillomavirus type 18 (HPV 18), but not to a corresponding HPV 16 peptide (HKSAIVTLTYDSEWQRDQ). Serum antibodies in the HPV 18 peptide were also demonstrated in these patients. The GILT motif resembles a common pattern present in many T-cell epitopes, and is located at the beginning of an 11-amino acid-long A-helix structure close to the carboxyterminal end of HPV 18 E2. We conclude that two epitopes (a T-helper cell epitope and a B-cell epitope) overlap in the HPV 18 E2.

The autologous mixed epidermal cell-T lymphocyte reaction is elevated in psoriasis: a crucial role for epidermal HLA-DR+/CD1a- antigen-presenting cells

The objective of this study was to determine whether epidermal cells (EC) from psoriasis lesions and uninvolved skin could stimulate autologous T lymphocytes in the in vitro autologous mixed epidermal cell-T lymphocyte reaction (autologous MECLR). The functional role of antigen-presenting cell (APC) subsets was concurrently determined in this reaction. Mononuclear cells and purified T lymphocytes from peripheral blood of psoriasis patients showed a clear proliferative response to autologous unpurified epidermal cells from involved as well as uninvolved skin. The autologous mixed leukocyte reaction (MLR) was not elevated in psoriasis patients. In healthy controls and contact allergy patients, T-lymphocyte proliferation was not observed either in the autologous MECLR or in the autologous MLR. The level of proliferation in the autologous MECLR from psoriasis patients correlated to the number of epidermal cells that were added. To exclude the possibility that the observed proliferation in the autologous MECLR in psoriasis was due to the presence of epidermal T lymphocytes that were being stimulated and expanded in vitro, the stimulator EC were gamma irradiated (30 Gy) in some experiments. Preincubation of EC with cyclosporin A (CsA) significantly inhibited the autologous MECLR. The CsA-induced inhibition could be neutralized by the addition of fresh untreated EC to these cultures. This indicated that one of the modes of action of CsA in resolving psoriasis is, as some investigators have already shown, via inhibition of epidermal accessory cell function. In the autologous MECLR, APC from psoriasis skin could initiate this reaction, whereas APC from peripheral blood could not. This occurred in an MHC class II restricted fashion. Depletion experiments showed that Langerhans cells (HLA-DR+/CD1a+) were not the principal stimulators of autologous T lymphocytes in the MECLR. These results indicated that mainly HLA-DR+/CD1a- epidermal cells from psoriasis patients could stimulate autologous peripheral blood T lymphocytes in an MHC class II-restricted fashion.

Autologous mixed lymphocyte reaction is reduced in patients with psoriasis

The autologous mixed lymphocyte reaction (auto-MLR) was studied to test the interactions between immunocompetent cells in patients with psoriasis. The auto-MLR in 20 patients with psoriasis was significantly lower than in 16 normal controls. Lower values were found in untreated psoriatic patients than in those in remission following treatment. The values in the latter group were significantly lower than in controls and in six patients with atopic dermatitis in remission. The tendency for an increase in the auto-MLR with a decrease in disease activity was further confirmed in five patients studied before and after treatment. In contrast, the allogeneic lymphocyte reaction (allo-MLR) in psoriatics was similar to that in normal controls.

The relationship of corneal Langerhans cells to herpes simplex antigens during dendritic keratitis

The corneal migration and topographic distribution of Langerhans cells (LC) in relation to herpes simplex virus antigens was studied during the course of dendritic keratitis in inbred mice. Corneal epithelial sheets from infected mice at selected time points were "double stained" for Ia-positive Langerhans cells and HSV antigens, using a sequential avidin biotin immunoperoxidase and glucose oxidase technique. The amount of HSV antigen was maximum at day 2 paralleling the clinical time course, with most corneal epithelium HSV antigen negative by day 8. LC were seen in peripheral corneas by day 2 and in paracentral and central cornea by day 8, with peak numbers detected between days 8 and 11 post-infection. Although HSV antigens and LC were simultaneously detected within corneal epithelium, LC were not observed in anatomic juxtaposition to HSV antigens, even after reinoculation of infected corneas with HSV on day 14 following the primary infection. These data suggest that local factors in the corneal epithelium other than HSV antigens per se may be chemotactic for LC during the course of dendritic keratitis.

Immediate decrease in antigen-presenting function and delayed enhancement of interleukin-1 production in human epidermal cells after in vivo UVB irradiation

Human skin was irradiated in vivo with a single UVB dose (100 mJ/cm2 or 200 mJ/cm2) to examine simultaneously the antigen-presenting function and interleukin-1 (IL-1) production capacity of irradiated epidermal cells (EC). Suction blisters were produced on irradiated areas on days 0, 3 and 7 after UVB. Irradiated EC were harvested and co-cultured with autologous T lymphocytes in the presence of antigens (PPD, HSV) or mitogen (ConA). Culture supernatants were tested for IL-1 activity using the thymocyte comitogenity assay. We found that a single 200 mJ/cm2 dose of UVB caused an immediate suppression of the antigen-presenting function of EC, but no alteration in their IL-1 production capacity or surface marker expression (ATPase, CDI). PPD- and HSV-induced lymphocyte proliferation was decreased 70-80% and ConA-driven proliferation 30% when compared to non-irradiated EC. However, this suppression was restored on days 3 and 7 after UVB irradiation, this being coexistent with an increased capacity of EC to produce IL-1. It remains to be elucidated whether the immediate UVB-induced photoimmunosuppression observed in the present study is due to inhibitory mediators or impaired membrane function of EC or both.

Basophil histamine release and lymphocyte proliferation tests in latex contact urticaria. In vitro tests in latex contact urticaria

Basophil histamine release and lymphocyte proliferation tests were examined with latex allergen prepared from surgical gloves in 15 patients with latex contact urticaria. The basophil histamine release test (BHRT) yielded positive results in 13/14 (93%) patients, whereas commercial latex RAST was positive in only 9/15 (60%) patients. Lymphocyte proliferation test (LPT) was positive in 3/15 (20%) patients, suggesting that cell-mediated immune reactions may also occur in latex allergy. However, patch tests to latex were negative and neither were epidermal Langerhans cells able to present latex antigen to T lymphocytes in vitro.

Immune responses to herpes simplex virus in patients with facial herpes simplex and those with eczema herpeticum

The immune response to herpes simplex virus (HSV) was studied in 59 patients with primary and recrudescent facial HSV infections. The patients included nine with atopic eczema, seven of whom had eczema herpeticum (EH). All patients had antibodies to HSV (measured by ELISA) and all but three had HSV-specific cell mediated immunity (CMI) (measured by in vitro lymphoproliferation). Thirteen control subjects were negative for both tests. All three patients with absent CMI to HSV had suffered from severe EH and had depressed CMI to HSV for several months following an attack. In two of these EH patients, a positive CMI response was produced by in vitro removal of CD8 + ve T lymphocytes from peripheral blood mononuclear cells using a panning technique. Thus the absence of CMI to HSV in these patients was due to suppressor cell function rather than a lack of specifically responsive cells. The other four EH patients with normal CMI to HSV had suffered less severe EH, but no association between the absence of CMI to HSV and serum IgE level or activity of the eczema was apparent in the atopic patients. No specific anti-HSV IgE antibody was detectable.