Kim B. Yancey

Immune-Mediated Subepithelial Blistering Diseases of Mucous Membranes: Pure Ocular Cicatricial Pemphigoid Is a Unique Clinical and Immunopathological Entity Distinct From Bullous Pemphigoid and Other Subsets Identified by Antigenic Specificity of Autoantibodies

BACKGROUND AND DESIGNnThere is much confusion in the clinical classification of immune-mediated subepithelial blistering diseases of mucous membranes. We conducted a 6-year comprehensive study to better classify this heterogeneous disease group. Indirect immunofluorescence was performed on a salt-split-skin substrate to detect circulating antibasement membrane antibodies (n = 47). Serologic reactivity against cultured keratinocyte antigens was examined by immunoblots (n = 38) and immunoprecipitation (n = 15). The results were correlated with the clinical features and direct immunofluorescence data of the entire patient group (n = 87) without preassignment of clinical diagnoses. chi 2 Statistical analyses compared these results with those of the classic bullous pemphigoid group (n = 36).nnnRESULTSnWhen compared with the bullous pemphigoid patients, a subset of patients with combined oral mucosal and skin lesions demonstrated marked similarity in direct and indirect immunofluorescence findings and in serologic reactivity to bullous pemphigoid antigens. By contrast, a subset of patients with only ocular lesions exhibited significantly lower in vivo deposits of IgG and C3, higher deposits of fibrin, virtual absence of circulating antibodies, and negative serologic reactivity to bullous pemphigoid antigens.nnnCONCLUSIONSnOcular patients without skin or mouth lesions, in particular those with negative indirect immunofluorescence, should be distinctively classified as ocular cicatricial pemphigoid, a unique clinical and immunopathologic entity. Patients with mucous membrane involvement who also demonstrate skin lesions and antibodies to the root of salt-split-skin substrate should be classified as anti-BP Ag mucosal pemphigoid, even though they may exhibit severe oral and/or ocular diseases. The remaining mucous membrane patients are heterogeneous. Some can be classified on the basis of autoantibodies to other basement membrane determinants, or if serum autoantibody negative, on the basis of clinical features (ie, pure oral mucosal pemphigoid or overlapping mucosal involvement).

Direct immunofluorescence microscopy of 1 mol/L sodium chloride-treated patient skin

Patients with bullous pemphigoid and those with epidermolysis bullosa acquisita often demonstrate virtually identical clinical, histologic, and immunopathologic features. Although some patients can be distinguished by their pattern of circulating IgG anti-basement membrane zone antibody binding to 1 mol/L sodium chloride-split human skin, approximately 20% and 50% of bullous pemphigoid and epidermolysis bullosa acquisita patients, respectively, do not possess such antibodies. Hence this study sought to determine whether these patients can be distinguished by mapping the distribution of basement membrane zone immunoreactants in patient skin split in vitro by 1 mol/L sodium chloride. All sodium chloride-treated samples from patients with bullous pemphigoid (n = 8), epidermolysis bullosa acquisita (n = 4), or other bullous skin diseases (n = 6) contained a lamina lucida cleavage plane bounded by bullous pemphigoid antigen and laminin; moreover, treatment of patient samples was performed without loss of tissue substrate or in situ immunoreactants. Deposits of IgG were found on the epidermal side of sodium chloride-treated skin from 13 of 14 bullous pemphigoid samples; IgG deposits in bullous pemphigoid samples were exclusively epidermal in eight, epidermal and dermal in five, and solely dermal in one. In contrast, IgG was found exclusively on the dermal side of sodium chloride-treated samples from patients with epidermolysis bullosa acquisita. Although IgG mapping distinguished bullous pemphigoid and epidermolysis bullosa acquisita patients in 94% of these samples, the distribution of C3 in sodium chloride-treated patient skin was more variable and less predictive diagnostically.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies From Patients With Localized and Generalized Bullous Pemphigoid Immunoprecipitate the Same 230-kd Keratinocyte Antigen

Two patients demonstrating the typical clinical, histologic, and immunopathologic features of nonscarring localized bullous pemphigoid are described. These patients possess circulating IgG autoantibodies that bind the epidermal side of 1.0-mol/L sodium chloride-split human skin in indirect immunofluorescence microscopy. Immunnoprecipitation studies demonstrate that these patients have circulating autoantibodies that immunoprecipitate the same 230-kd bullous pemphigoid antigen that is precipitated by autoantibodies from patients with generalized bullous pemphigoid. These findings indicate that localized bullous pemphigoid is a true clinical variant of generalized pemphigoid rather than a separate nosologic entity.

Inflammatory properties of human C5a and C5a des Arg/ in mast cell-depleted human skin.

C5a and its degradation product, C5a des Arg, elicit immediate cutaneous inflammatory reactions after intradermal injection. Histologically, these reactions are characterized by neutrophil-rich leukocytic infiltrates, leukocytoclasis, edema, and dermal mast cell degranulation. It has not been possible to assess in vivo the relative contributions of resident mast cells and circulating leukocytes to this reaction because the accumulation of leukocytes and degranulation of mast cells occur simultaneously after injection of these anaphylatoxins. To assess the role of mast cells in these inflammatory reactions, we have examined the reactivity of human skin selectively depleted of dermal mast cells by local corticosteroid treatment. Corticosteroid-treated skin became virtually devoid of dermal mast cells within 4-6 wk as assessed by light microscopy, immunofluorescence with fluorescein-conjugated avidin, or electron microscopy. Mast cell-depleted skin demonstrated normal vasopermeability and vasodilatory responsiveness to intradermal injection of histamine, but the reactivity of these sites to the mast cell secretagogue, morphine, was absent. Moreover, no clinical reactions were detectable in mast cell-depleted human skin after intradermal challenge with 50 ng of either C5a or C5a des Arg, despite the fact that biopsies of these sites revealed substantial, neutrophil-rich infiltrates. These infiltrates were qualitatively and quantitatively identical to C5a or C5a des Arg-induced infiltrates in mast cell replete skin. This experimental approach in vivo has allowed the independent analysis of the anaphylactogenic and chemoattractant activities of human C5a and C5a des Arg in human skin, demonstrated the importance of dermal mast cells in these clinical responses, and shown that leukocytes can accumulate at these injection sites directly in response to these mediators.

C5a as a mediator of cutaneous inflammation

C5a is an 11,000-dalton fragment of the fifth component of complement with potent anaphylatoxic and leukocyte chemotactic activities. Because C5a may play an important role in selected skin disorders as well as in systemic diseases with cutaneous manifestations, we have studied the clinical and histologic alterations produced by the intradermal injection of this potent soluble mediator of inflammation in human skin in vivo. These studies have outlined the biologic properties of human C5a within the context of cells resident in the skin, the cutaneous microvasculature, and interacting cellular elements of peripheral blood.

Role of C5a in the induction of tumoricidal activity in C3H/HeJ (Lpsd) and C3H/OuJ (Lpsn) macrophages.

Thioglycollate‐elicited macrophages from C3H/HeJ (Lpsd) and C3H/OuJ (Lpsn) mice were cultured in a two‐signal, tumoricidal assay using recombinant interferon‐γ (rlFN‐γ) as the “priming” signal and recombinant human C5a (rC5a) as the “trigger” signal. These experiments were compared directly with a well established, two‐signal tumoricidal assay in which rlFN‐γ was used as the “priming” signal and protein‐rich, butanol‐extracted lipopolysaccharide (But‐LPS) as the “trigger” signal. These studies showed that rlFN‐γ‐primed macrophages can be triggered in a dose‐dependent manner by rC5a to effecthigh levels of tumoricidal activity. Maximum levels of cytotoxicity achieved using this endogenously produced, biologically active peptide as a “trigger” signal were comparable to those obtained using But‐LPS. Moreover, experiments in which anti‐C5 antibody was included in macrophage cultures stimulated with rlFN‐γ and But‐LPS showed a significant reduction (P < .05) in tumoricidal activity. Because LPS has been shown to induce macrophage C5 production and enzyme release, these findings suggest that macrophage‐derived C5 is locally converted to C5a (or some other biologically active C5 cleavage fragment), which functions as an autocrine trigger signal for the induction of tumoricidal activity. In summary, these data suggest 1) that rC5a can provide a “second signal” to rlFN‐γ‐primed murine macrophages for the induction of tumoricidal activity and 2) that macrophage‐derived C5 or C5a may represent an autocrine signal induced by exogenous “trigger signals.”