Omalizumab therapy for bullous pemphigoid.

BACKGROUND: Bullous pemphigoid (BP) responds to a variety of immunosuppressive agents and usually controls, but does not cure, the disease. Omalizumab, Food and Drug Administration-approved for asthma, selectively suppresses the activity of IgE, an important immunoglobulin in the pathogenesis of BP. OBJECTIVE: We wished to determine if systemic omalizumab would have a therapeutic effect in patients with BP. METHODS: We treated 6 patients with BP using omalizumab and followed up their disease for up to 42 months. RESULTS: Although variable, 5 of the 6 patients with BP received therapeutic benefit from systemic omalizumab (the sixth terminated treatment because of intercurrent illness) with less use of other immunosuppressants, inhibition of new bullae, less pruritus, and dramatic decreases in eosinophil counts. None of the patients had untoward side effects from omalizumab. LIMITATIONS: This was an open, uncontrolled study. CONCLUSIONS: Omalizumab neutralizes the activity of IgE in patients with BP and improves the control of their disease activity.

Accelerated CD8+ T-cell memory and prime-boost response after dendritic-cell vaccination.

Efficient boosting of memory T-cell numbers to protective levels generally requires a relatively long interval between immunizations. Decreasing this interval could be crucial in biodefense and cancer immunotherapy, in which rapid protective responses are essential. Here, we show that vaccination with peptide-coated dendritic cells (DCs) generated CD8+ T cells with the phenotype and function of memory cells within 4-6 d. These early memory CD8+ T cells underwent vigorous secondary expansion in response to a variety of booster immunizations, leading to elevated numbers of effector and memory T cells and enhanced protective immunity. Coinjection of CpG oligodeoxynucleotides, potent inducers of inflammation that did not alter the duration of DC antigen display, prevented the rapid generation of memory T cells in wild-type mice but not in mice lacking the interferon (IFN)-gamma receptor. These data show that DC vaccination stimulates a pathway of accelerated generation of memory T cells, and suggest that events of inflammation, including the action of IFN-gamma on the responding T cells, control the rate of development of memory CD8+ T cells.

Estrogen regulation of immune responses after injury.

There is a naturally occurring gender difference in immune responses which persists after traumatic injury. Physiological levels of 17beta-estradiol (E(2)) are immunostimulatory, whereas high pregnancy and superphysiological levels are immunosuppressive. In contrast, at all concentrations, testosterone suppresses immune responses. Evidence from this laboratory and others suggest that the gender difference in immune responses after injury is mediated in part by alterations in the circulating levels of gonadal steroid hormones through modulation of production of inflammatory and immunoregulatory cytokines, including interleukin-6 (IL-6). Aberrant production of IL-6 is known to be an important mediator of immunity after injury. Since E(2) is a critical regulator of IL-6 production and overall immune function, it suggests gender specific therapies should be considered for the treatment of patients.

Ethanol and burn injury: estrogen modulation of immunity.

A good deal of clinical evidence supports the idea that ethanol exposure is a causative factor in the occurrence of burn or other traumatic injury. In addition, more recent evidence reveals that individuals who sustain injury while under the influence of ethanol suffer from increased morbidity and mortality compared with those with comparable injuries who did not consume ethanol. Many of the complications seen in ethanol-exposed, burn-injured subjects result from depressed immune responses, which render the host unable to fight off infectious organisms. Both injury and ethanol exposure independently affect cellular immune responses, including delayed-type hypersensitivity and splenocyte proliferative responses, and the combined insult of ethanol exposure and injury acts in conjunction to increase further the magnitude and duration of immunosuppression. It is interesting that these immune responses can be restored experimentally in male, but not in female, mice by administration of low, proestrous levels of estrogen. The complexity of the responses after injury in ethanol-exposed subjects is multiplied when the sex of the subjects is added to the equation. This is due, in part, to the effect of the combined insult of injury and ethanol on the production of gonadal steroid hormones in males and females and the direct effects of those hormones on cytokine gene expression in sensitive cell types such as the macrophage. Evidence seems to indicate that cellular immune responses after ethanol exposure and burn injury differ in kinetics and magnitude for male and female subjects, and, hence, the therapeutic interventions to treat burn-injured patients should take into account both sex and ethanol exposure.

Functional characterization of an IgE-class monoclonal antibody specific for the bullous pemphigoid autoantigen, BP180.

BP180 (collagen XVII) is the target antigen in several autoimmune diseases including bullous pemphigoid (BP). Both IgE and IgG class autoantibodies have been shown to be pathogenic in BP; however, studies designed to elucidate the patho-mechanisms mediated specifically by the IgE-class autoantibodies are limited by the low levels (ng/mL) of IgE in human sera. In this report, we developed mouse IgE class monoclonal antibodies (MAbs) against the immunodominant NC16A domain of the human BP180 protein and characterized two of the resultant MAbs, designated 395A5 and 395D2. Epitope mapping studies revealed that both MAbs target segment 2 of NC16A, as was described for IgE and IgG class BP autoantibodies. Also similar to BP IgE, MAb 395A5 showed indirect immunofluorescence labeling of the basement membrane zone (BMZ) of human skin, stimulated histamine release from mast cells when triggered with NC16A, and induced keratinocyte production of IL-8. The 395D2 MAb was also able to trigger antigen-specific histamine release from mast cells; however, in contrast to BP IgE and 395A5, 395D2 did not label the cutaneous BMZ, nor did it induce IL-8 production in keratinocytes. In summary, these studies underscore the importance of functionally characterizing MAbs generated for use in human disease models. The 395A5 IgE class murine MAb was shown to share several key functional properties with the pathogenically active IgE produced by BP patients. We therefore expect that this MAb will prove to be a useful tool for dissecting the mechanisms used by BP180-NC16A-specific IgE antibodies in the induction of BP skin lesions.

Pregnant women have increased incidence of IgE autoantibodies reactive with the skin and placental antigen BP180 (type XVII collagen).

BP180 (type XVII collagen) is a transmembrane protein expressed in a variety of cell types. It is also the target of autoantibodies in cutaneous autoimmune disease including bullous pemphigoid and pemphigoid gestationis, a disease unique to pregnancy. The purpose of this study was to determine the prevalence and specificity of cutaneous autoantibodies in a cohort of pregnant women. De-identified sera were collected from pregnant women (n=299) and from non-pregnant controls (n=134). Sera were analyzed by ELISA for the presence of IgG and IgE autoantibodies directed against several cutaneous autoantigens. IgE antibodies against the NC16A domain of BP180 were detected in 7.7% of pregnant women, compared to 2.2% of healthy controls (p=0.01). No increase in total or cutaneous autoantigen specific IgG was seen. Total serum IgE was within the normal range. Full-length BP180 was detected by western immunoblot in epidermal, keratinocyte, placental and cytotrophoblast (CTB) cell lysates. Furthermore, flow cytometry and indirect immunofluorescence confirmed the expression of BP180 on the surface of cultured CTBs. Finally, it was demonstrated that IgE antibodies in the pregnancy sera labeled not only cultured CTBs, but also the placental amnion and cutaneous basement membrane zone using indirect immunofluorescence. We conclude that some pregnant women develop antibodies specific for BP180, and that these autoantibodies are capable of binding both CTB and the placental amnion, potentially affecting placental function.

A novel ELISA reveals high frequencies of BP180-specific IgE production in bullous pemphigoid.

Bullous pemphigoid (BP) is a humoral autoimmune disease directed predominantly against the non-collagenous NC16A domain of the BP180 hemidesmosomal protein. Our laboratory has recently shown, using a mouse xenograft model, that passive transfer of IgE autoantibodies from BP sera induces a skin phenotype that recapitulates the early phases of the disease. Herein, we describe the development of a highly specific and sensitive ELISA to detect circulating IgE autoantibodies that recognize BP180-NC16A. Using this assay, we detected NC16A-specific IgE-class autoantibodies in 77% of BP sera. This frequency, which is significantly higher than reported previously, is comparable to that of anti-NC16A IgG autoantibody production. In 3 BP patients monitored over time, the circulating NC16A-specific levels of both IgE and IgG were associated with clinical disease activity; however, patient sera did not always contain high levels of both isotypes. In conclusion, our ELISA provides a highly sensitive and specific tool for the detection of BP180-specific IgE in patient sera. Furthermore, we report that the majority of BP sera contain both IgE and IgG class autoantibodies specific for NC16A and suggest that screening for both isotypes of autoantibodies may provide a better diagnostic value than IgG alone.