Epidermal HLA-DR and the enhancement of cutaneous reactivity to superantigenic toxins in psoriasis.

Streptococcal and staphylococcal superantigens (SAg's) have been implicated in the pathogenesis of inflammatory skin diseases, but the mechanisms by which these toxins act are unknown. The present study assessed the ability of nanogram quantities of topically applied purified toxic shock syndrome toxin-1 (TSST-1), staphylococcal enterotoxin type B, and streptococcal pyrogenic enterotoxin types A and C to induce inflammatory reactions in clinically uninvolved skin of normal controls and subjects with psoriasis, atopic dermatitis, and lichen planus. These SAg's triggered a significantly greater inflammatory skin response in psoriatics than in normal control subjects or in subjects with atopic dermatitis or lichen planus. Surprisingly, skin biopsies did not exhibit the T-cell receptor Vbeta stimulatory properties predicted for SAg-induced skin reactions. By 6 hours after patch testing with SAg's, TNF-alpha mRNA had increased in the epidermis (but not the dermis) in biopsies from psoriatics, compared with controls. Immunohistochemical studies revealed significantly higher HLA-DR expression in keratinocytes from psoriatics than from controls. However, a mutant TSST-1 protein that fails to bind HLA-DR did not elicit an inflammatory skin reaction. These results indicate that keratinocyte expression of HLA-DR enhances inflammatory skin responses to SAg's. They may also account for previous studies failing to demonstrate selective expansion of T-cell receptor Vbetas in psoriatics colonized with SAg-producing Staphylococcus aureus, and they identify a novel T cell-independent mechanism by which SAg's contribute to the pathogenesis of inflammatory skin diseases.

Cutaneous exposure to the superantigen staphylococcal enterotoxin B elicits a T-cell-dependent inflammatory response.

We analyzed the impact of superantigens secreted by skin-colonizing Staphylococci on the skin and the associated lymphoid tissue following epicutaneous application and intracutaneous injection of small amounts of staphylococcal enterotoxin B (SEB). A single intracutaneous injection of 50 ng of SEB elicited a strong inflammatory response in the skin of BALB/c mice. Three to 6 h later, we observed langerhans cell activation, mast cell degranulation, vasodilation, upregulation of ICAM-1, and induction of VCAM-1 on dermal blood vessels, with vascular adhesion of granulocytes. by 12 to 24 h, cell infiltration of the dermis increased, reaching the epidermis. Among the infiltrating leukocytes, a substantial number of eosinophils was found. After 48 h, the infiltrate was dominated by mononuclear cells. The response to SEB was dose-dependent, and signs of inflammation slowly disappeared over 5 to 7 days. Although the induction of VCAM-1 on dermal blood vessels suggested a role for interleukin-1/tumor necrosis factor-alpha in this reaction, the activation of monocytes/macrophages was not able to substitute for lymphocytes, as severe combined immunodeficiency (SCID) mice (which are lymphocyte-deficient) did not mount an inflammatory skin response to intradermal injection of SEB. The fact that nude mice (T-cell-deficient) also did not mount an inflammatory response to SEB indicated the T-cell dependency of the response. The V beta specificity of the SEB effect was demonstrated by the fact that SJL/J mice, which lack V beta 8+ T cells (the major SEB-reactive T cell population in mice), exhibited much weaker responses. Deletion or tolerization of SEB-reactive V beta T cells was not observed after a single intradermal injection of such minute amounts of SEB.

Evidence for superantigen involvement in cardiovascular injury due to Kawasaki syndrome.

Kawasaki syndrome (KS), the major cause of acquired heart disease in children, is an acute multisystem vasculitis frequently associated with the development of myocarditis and coronary artery abnormalities. Despite the widely held belief that KS is an infectious disease, its etiology has remained elusive. Recently, we and others have reported the selective expansion of V beta 2+ T cells in the peripheral blood of most patients in the acute, but not in the convalescent, phase of KS. These data were consistent with the concept that this illness is triggered by a bacterial superantigen. We report here that a patient who died of acute KS had selective expansion of V beta 2+ T cells in her myocardium and coronary artery. Sequence analysis of TCR beta-chain genes of V beta 2+ T cells from the myocardium showed extensive junctional region diversity. These observations, along with the demonstration of V beta 2 expansion in both the CD4+ and CD8+ T cell subsets, support the concept that the activation of infiltrating V beta 2+ T cells are involved in the cardiovascular damage associated with KS.

Liver T cell subsets and adhesion molecules in murine graft-versus-host disease.

Murine GVHD across multiple minor histocompatibility barriers (B10.D2 into irradiated BALB/c) results in cell-mediated destruction of bile ducts inside the liver. Similar changes are characteristic of hepatic GVHD in humans following BMT. We have defined the phenotypes of inflammatory cells and the accessory/adhesion molecules expressed in the liver between day 7-14 of murine GVHD. T cells (CD3+) comprised 65% of hepatic inflammatory cells. alpha-beta and gamma-delta cells accounted for 92 and 8%, respectively of hepatic T cells. The percentage of CD4+ cells (29%) was 3 times that of CD8+ cells (11%). Lymphocyte function-associated antigen-1 (LFA-1) was expressed by the majority of inflammatory cells. Thirty per cent of the cells were positive for Mac-1, a differentiation marker of macrophages, large granular lymphocytes, and natural killer cells. Expression of intercellular adhesion molecule-1 and major histocompatibility complex class II (IAd) molecules on bile duct epithelial and portal vein endothelial cells was induced during GVHD. These results suggest that hepatic GVHD is induced by donor alpha-beta T cells through mechanisms that may involve CD4:1Ad and LFA-1:ICAM-1 interactions.

Increased ICAM-1 expression in the early stages of murine chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is considered to be a model for scleroderma, and vascular changes are considered to be important in that disease. We have examined the expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1) using monoclonal antibodies and immunohistochemistry in very early murine cGVHD. ICAM-1 is found on a number of cell types including endothelial cells. It is the natural ligand for LFA-1 found on leukocytes. Adherence of leukocytes to ICAM-1 positive cells is mediated by LFA-1 and this binding is thought to play an important role in a number of cell adhesion events in immune reactions. Experimental cGVHD across minor histocompatibility barriers is established by the iv inoculum of B10.D2 spleen cells into a sublethally irradiated BALB/c host. Ear and skin biopsies were taken at Days 0-5 and from Days 14 to 120 postinoculum. In comparison to the control group (BALB/c spleen cells given to a sublethally irradiated BALB/c host), the cGVHD mice show increased ICAM-1 expression by Day 3 on endothelial cells and mononuclear cells (MNC) and on fibroblast-like cells by Day 4. By Day 14, there are increasing numbers of ICAM-1-expressing cells and increased epidermal reactivity for ICAM-1; and finally, an increased number of LFA-1 positive infiltrating MNC. These changes wane by Day 28 and are gone by Day 120. These results support the concept that ICAM-1/LFA-1 interactions play a role in the immune regulation of cGVHD. The very early upregulation of ICAM-1 on the endothelium indicates that this cell type may be playing a primary role in cGVHD, and this model should provide a simple system in which to test regulation of endothelial activation in vivo.

The effects of inhaled interferon gamma in normal human airways.

Recent studies suggest that cytokines such as recombinant interferon-gamma (rIFN-gamma) may play a role in the treatment of certain respiratory conditions associated with infection and inflammation. This study was designed to determine if rIFN-gamma could be delivered effectively in a group of normal human volunteers. The effectiveness of the inhaled delivery system was demonstrated by the recovery of free IFN-gamma in bronchoalveolar lavage (BAL) fluid and macrophage (M phi) expression of IP-10, an IFN-gamma-inducible molecule, after therapy but not at baseline. IL-1 beta, but not IL-8, gene transcripts also showed evidence for up-regulation after rIFN-gamma therapy. Compared with baseline, inhaled rIFN-gamma did not significantly alter clinical symptom scores, spirometry, morning peak expiratory flow rate (PEFR), or the response to methacholine. Of interest, the evening PEFR increased significantly (p = 0.02), from 568 +/- 36 L/min at baseline to 584 +/- 33 L/min after inhaled rIFN-gamma. Although there was no significant change in total white cell count in BAL fluid, the cellular composition did demonstrate a significant decrease in percentage of alveolar M phi (p = 0.02) and an increase in percentage of lymphocytes (p = 0.02) after rIFN-gamma. There were no histologic differences seen in bronchial biopsy specimens, and there was no evidence for up-regulation of ICAM-1 or HLA-DR expression after rIFN-gamma. We conclude that, in normal persons, rIFN-gamma can be effectively delivered by inhalation. Future trials using inhaled rIFN-gamma appear to be warranted for certain pulmonary diseases.

Mast cell immunohistochemistry: non-immunological immunostaining mediated by non-specific F(ab')2-mast cell secretory granule interaction.

During investigations of murine and human mast cell immunoreactivity with potential anti-interleukin-4 antibodies, non-specific, non-immunological labelling of mouse and human mast cells became apparent. Non-specific, non-immunological labelling was identified by (i) immunolabelling of mast cells when using control isotype primary antibodies, (ii) ability of conjugated secondary antibodies to label mast cells without prior mast cell exposure to a primary antibody, (iii) extinction of the non-specific labelling and retention of specific labelling when the pH of the diluting and washing buffers is shifted from pH 7.2 to pH 6.0, and (iv) reduction/extinction of the labelling when the antibodies are pre-incubated with soluble heparin prior to immunostaining. The site of the reactivity on the electron microscope level was shown to be confined to the mast cell secretory granules. The results of this study support the hypothesis that non-specific labelling of mast cells results from an ionic interaction between the F(ab')2 segments of antibodies and the heparin constituent of the mast cell secretory granules. This study points out the necessity of stringent controls when using immunohistochemistry to determine mast cell reactivity to various antibodies.

Endothelial and fibroblastic activation in scleroderma. The myth of the "uninvolved skin".

We studied the immunohistochemistry of the skin of scleroderma patients to determine the differences (if any) between clinically "affected" and "nonaffected" areas. We examined paired skin biopsy samples from clinically involved forearm skin ("affected") and clinically uninvolved proximal skin ("nonaffected") taken from 19 patients with diffuse scleroderma and from 15 normal control subjects. We stained the sections with antibodies to endothelial leukocyte-adherence molecule type 1 (ELAM-1; to detect endothelial activation) and to procollagen-1 (PC-1; to detect newly formed, unprocessed collagen). There was increased expression of ELAM-1 and PC-1 in sclerodermatous skin as compared with the controls, but there was no difference between clinically affected and nonaffected skin samples. In 10 of 11 patients whose condition was getting worse, endothelial and fibroblast activation preceded fibrosis. Endothelial and fibroblast activation are more widespread in the skin of scleroderma patients than is evident by inspection on physical examination. What appears to be "normal" skin in diffuse scleroderma is already pathologic, as shown by abnormal endothelial activation and procollagen production.

Dermal mast cell degranulation in systemic sclerosis.

Paired biopsy samples from involved and uninvolved skin were obtained from 19 patients with generalized scleroderma (11 with early, progressive disease and 8 with late, improving disease). Skin biopsy samples were double stained for mast cell granules and for mast cell membrane. The number of mast cells was increased in patients with systemic sclerosis (SSc), in both involved and uninvolved skin and in both early and late disease. There was an increase in the number of degranulated mast cells in the involved skin of patients with both early and late disease and in the not-yet-involved skin of patients with early disease; however, there was no increase in the number of degranulated mast cells in areas of previously involved but now normal skin of patients with late disease. Increases in mast cell number and degranulation precede clinically apparent dermal fibrosis in SSc. These observations and the absence of mast cell degranulation in regressing skin suggest a participatory role of the mast cell in the clinical progression of skin changes in SSc.

Immunologic dysfunction in scleroderma: evidence for increased mast cell releasability and HLA-DR positivity in the dermis.

To investigate the role of mast cells and cell-mediated immunity in the pathogenesis of scleroderma, we studied wheal size after skin testing with compound 48/80, a liberator of mast cell histamine, and demonstrated increased mast cell releasability in skin that appeared normal, adjacent to involved skin. Immunofluorescent staining for HLA-DR showed dermal positivity in 12 of 13 involved- and 9 of 13 uninvolved-skin biopsy specimens from scleroderma patients, compared with only 1 of 10 controls. By immunoperoxidase staining, most of the DR positivity was found in fibroblast-like cells. These findings further support the notion of immunologic dysfunction in scleroderma.

An immunopathological study of herpes-associated erythema multiforme.

Any pathogenetic mechanism proposed for erythema multiforme (EM) must account for the prominent mononuclear cell infiltrate in the skin lesions. The purpose of this study was to characterize immunopathologically, with monoclonal antibodies to human leukocyte antigens, the inflammatory cells in early target lesions of recurrent herpes-associated EM. Cryostat sections of snap-frozen skin biopsies were studied by the avidin-biotin immunoperoxidase technique with use of the following monoclonal antibodies: anti-HLA-DR, anti-Leu M5, anti-Leu 4 + 5b, anti-Leu 3a + 3b, anti-Leu 2a, anti-Leu 14, and anti-Leu 6. The dermal mononuclear inflammatory infiltrate in the EM biopsies consisted of monocyte-macrophages and T-lymphocytes, with both helper and suppressor T cells present. Both the dermal inflammatory infiltrate and the overlying keratinocytes were strongly HLA-DR positive. No definite alteration of Langerhans cell number or distribution was noted. These findings are consistent with the characteristics seen in cell-mediated immune reactions in the skin and point to this as a likely immune mechanism for the tissue damage of EM.

Lymphocyte subpopulations in the skin of patients with chronic urticaria.

In order to characterize the nature of the mononuclear cells in the perivascular infiltrates in the skin of 11 patients with CU, skin biopsy specimens were analyzed in situ by an avidin-biotin immunoperoxidase technique. Serial frozen sections were stained for total T cells, helper-inducer T cells, suppressor-cytotoxic T cells, B cells, monocytes/macrophages, and HLA-DR antigen. The infiltrates were found to consist mainly of T cells, whereas B cells and macrophages were rarely seen. Most of the T cells possessed the T4+ helper phenotypes, whereas smaller numbers of infiltrating cells were defined as suppressor-cytotoxic cells. Most of the helper-inducer T cells coexpressed the Ia (HLA-DR) antigen. Several potential pathogenic mechanisms could be implicated in CU based on these observations.