Preparing Patients for Oral Immunotherapy (PPOINT): International Delphi consensus for procedural preparation and consent

BACKGROUND

Despite the promise of oral immunotherapy (OIT) to treat food allergies, this procedure is associated with potential risk. There is no current agreement about what elements should be included in the preparatory or consent process.

OBJECTIVE

We developed consensus recommendations about the OIT process considerations and patient-specific factors that should be addressed before initiating OIT and developed a consensus OIT consent process and information form.

METHODS

We convened a 36-member Preparing Patients for Oral Immunotherapy (PPOINT) panel of allergy experts to develop a consensus OIT patient preparation, informed consent process, and framework form. Consensus for themes and statements was reached using Delphi methodology, and the consent information form was developed.

RESULTS

The expert panel reached consensus for 4 themes and 103 statements specific to OIT preparatory procedures, of which 76 statements reached consensus for inclusion specific to the following themes: general considerations for counseling patients about OIT; patient- and family-specific factors that should be addressed before initiating OIT and during OIT; indications for initiating OIT; and potential contraindications and precautions for OIT. The panel reached consensus on 9 OIT consent form themes: benefits, risks, outcomes, alternatives, risk mitigation, difficulties/challenges, discontinuation, office policies, and long-term management. From these themes, 219 statements were proposed, of which 189 reached consensus, and 71 were included on the consent information form.

CONCLUSION

We developed consensus recommendations to prepare and counsel patients for safe and effective OIT in clinical practice with evidence-based risk mitigation. Adoption of these recommendations may help standardize clinical care and improve patient outcomes and quality of life.

Age-Related Food Aversion and Anxiety Represent Primary Patient Barriers to Food Oral Immunotherapy

BACKGROUND

Although oral immunotherapy (OIT) for food allergy is a reasonable treatment option, barriers to this procedure's implementation have not been extensively evaluated from a patient perspective.

OBJECTIVE

We evaluated the barriers patients face during OIT administration, including anxiety and taste aversion, and the role of health care professionals, especially dietitians.

METHODS

A survey in Canada and the United States involved families currently enrolled in food OIT programs.

RESULTS

Of responses from 379 participants, fear of reaction was the most common barrier to OIT initiation, with 45.6% reporting it being a "very significant" barrier with other fears reported. However, taste aversion represented the prominent obstacle to continuation. Taste aversion was associated with a slower buildup (P = .02) and a reduction in dose (P = .002). Taste aversion was a strongly age-dependent barrier for initiation (P < .001) and continuation (P < .002), with older children over 6 years of age reporting it as a very significant barrier (P < .001). Boredom was reported as a concern for specific allergens such as peanut, egg, sesame, and hazelnuts (P < .05), emphasizing the need for diverse food options. Notably, 59.9% of respondents mixed OIT foods with sweet items. Despite these dietary concerns, dietitians were underutilized, with only 9.5% of respondents having seen a dietitian and the majority finding dietitian support helpful with greater certainty about the exact dose (P < .001).

CONCLUSIONS

Taste aversion and anxiety represent primary patient-related barriers to OIT. Taste aversion was highly age dependent, with older patients being more affected. Dietitians and psychology support were underutilized, representing a critical target to improve adherence and OIT success.

Real-world safety and effectiveness analysis of low-dose preschool sesame oral immunotherapy

Background

Previous studies support the effectiveness of sesame oral immunotherapy (S-OIT) in patients >4 years old using maintenance doses of 1200 mg protein. However, tahini is often not palatable to children, and high-maintenance doses may not be possible for preschoolers.

Objective

We studied the safety and effectiveness outcomes of preschoolers with sesame allergy who underwent low-dose S-OIT of 200 mg protein.

Methods

Preschoolers with sesame allergy, with a history of objective reaction to sesame, and with either a positive skin prick test result (wheal diameter ≥3 mm) or sesame-specific IgE level ≥0.35 kU/L were included. Doses were escalated every 2 to 4 weeks until the maintenance dose of 200 mg of sesame protein was reached. The maintenance dose was continued daily for 1 year, followed by exit oral food challenge (OFC). Primary safety outcomes included allergic reactions grade 2 or higher and the need for epinephrine therapy during buildup. The primary effectiveness outcome was proportion of patients tolerating a minimum of 2000 mg sesame protein at exit OFC.

Results

Twenty-eight preschoolers (median age, 33.5 months) were enrolled to receive S-OIT. During the buildup phase, 9 subjects (32.1%) had no reaction, and 8 (28.6%) and 11 (39.3%) had grade 1 and 2 reactions, respectively. One patient (3.57%) received epinephrine for a grade 2 reaction. Twenty-one (91.3%) of 23 eligible subjects underwent exit OFC; 18 (85.7%) of these 21 patients successfully completed exit OFC. One (4.8%) and 2 (9.5%) subjects had grade 1 and 2 reactions, respectively, during OFC.

Conclusions

A lower and age-appropriate maintenance dose is safe and effective in desensitizing preschoolers with sesame allergy.

Risk factors associated with safety of preschool peanut oral immunotherapy

Background

An understanding of how patient characteristics such as age, baseline peanut-specific IgE, and atopic comorbidities may influence potential safety outcomes during peanut oral immunotherapy (P-OIT) could aid in shared decision making between clinicians and patient families.

Objective

This study explored the relationship between baseline patient characteristics and reactions during P-OIT using a large sample size to better understand potential risk factors influencing P-OIT safety.

Methods

Data were obtained from the Food Allergy Immunotherapy (FAIT) registry, which collects real-world OIT data from community and academic allergy clinics across Canada. Multivariable logistic regression modeling was performed to examine the relationship between baseline patient characteristics and reactions during P-OIT. Multiple imputation was applied to reduce potential bias caused by missingness and to maximize the use of available information to preserve statistical power.

Results

Between April 2017 and June 2021, a total of 653 eligible patients initiated P-OIT. Multivariable regression analysis showed pre-OIT grade 2+ initial reaction (odds ratio [OR] = 1.33, 95% confidence interval [CI] 1.10, 1.61), allergic rhinitis (OR = 1.60, 95% CI 1.08, 2.38), older age (OR = 1.01, 95% CI 1.00, 1.02), and higher baseline peanut-specific IgE (OR = 1.02, 95% CI 1.02, 1.03) were associated with grade 2+ reaction during P-OIT after adjusting for potential risk factors.

Conclusion

Our study identified several clinically important risk factors for grade 2+ reactions during P-OIT: pre-OIT grade 2+ initial reaction, allergic rhinitis, older age, and higher baseline peanut-specific IgE. These results highlight the need for individualized risk stratification for OIT.

Comparing the risk of anaphylaxis requiring epinephrine in oral immunotherapy and subcutaneous immunotherapy: A review of recent Canadian real-world literature

Background

The safety of pediatric food oral immunotherapy (Ped-OIT) has been depicted by some as less favorable than subcutaneous immunotherapy (SCIT) owing to the increased number of serious adverse events requiring epinephrine. A review of real-world data comparing Ped-OIT and SCIT safety is necessary to guide shared decision making.

Objectives

Our aim was to compare the safety and adverse event profiles of peanut Ped-OIT and SCIT using Canadian real-word literature.

Methods

We performed a retrospective review of recent Canadian real-world literature on peanut Ped-OIT and SCIT safety and adverse events.

Results

The incidences of systemic reactions requiring epinephrine were 11 in 270 patients (4.07%) and 12 in 41,020 doses (0.029%) in a multicenter study in British Columbia, Alberta, Manitoba, and Nova Scotia studying 270 preschool-age children treated with peanut OIT. Similarly, a multicenter study in South-Western Ontario examining 160 patients between the ages of 1 and 17 years who were treated with peanut OIT showed that the incidences of systemic reactions requiring epinephrine were 5 in 160 patients (3.1%) and 8 in 52,751 doses (0.015%). A single-center retrospective review of 380 patients receiving aeroallergen SCIT showed that the incidences of systemic reactions requiring epinephrine were 28 in 380 patients (7.4%) and 1 in 1047 injection visits (0.095%). These findings are comparable to those of a review of 860 patients in Ontario who received either aeroallergen or venom SCIT, in which the incidence of systemic reaction requiring epinephrine was 10 in 4242 injections (0.24%).

Conclusion

Despite differences in the OIT protocols used and age groups studied, recent real-world data suggest that the safety of preschool peanut OIT or peanut OIT using a slower buildup schedule is comparable to that of SCIT.

Real-World Safety Analysis of Preschool Tree Nut Oral Immunotherapy

BACKGROUND

Our group previously described preschool peanut oral immunotherapy (OIT) in a real-world, multicenter setting, suggesting that this therapy is safe for most preschoolers.

OBJECTIVE

To examine the safety and tolerability of tree nut (TN) OIT in preschoolers in the real world.

METHODS

As part of a Canada-wide quality improvement project, TN-OIT (cashew/pistachio, walnut/pecan, hazelnut, almond, and macadamia nut) was performed in preschoolers who had (1) a skin prick test wheal diameter greater than or equal to 3 mm or a specific IgE level greater than or equal to 0.35 kU/L and a convincing objective IgE-mediated reaction or (2) no ingestion history and a specific IgE level greater than or equal to 5 kU/L. Dose escalations were performed every 2 to 4 weeks till a maintenance dose of 300 mg of TN protein was reached. Symptoms were recorded and classified using the modified World Allergy Organization Subcutaneous Immunotherapy Reaction Grading System (1, mildest; 5, fatal).

RESULTS

Of the 92 patients who started TN-OIT from 2018 to 2021, 79 (85.9%) underwent single-food TN-OIT and 13 (14.1%) underwent multifood TN-OIT to 2 (10.8%) or 3 (3.3%) TNs. Eighty-nine (96.7%) patients reached maintenance, and 4 (4.3%) dropped out. Sixty-five (70.7%) patients experienced reactions during buildup: 35 (38.0%) grade 1 reactions, 30 (32.6%) grade 2 reactions, no grade 3 or 4 reactions, and 2 (2.17%) received epinephrine.

CONCLUSIONS

Preschool TN-OIT in a real-world, multicenter setting appears safe and tolerable, with results comparable with our previously reported peanut OIT findings.

The Case for Prompt Salvage Infant Peanut Oral Immunotherapy Following Failed Primary Prevention

Recent guideline recommendations have shifted from recommending prolonged avoidance of allergenic foods in the first 3 years of life to a primary prevention approach involving the deliberate early introduction to infants at risk of developing food allergy. Despite this, some infants, especially those with severe eczema who are at highest risk for developing peanut allergy, fail to receive the preventative benefits of early peanut introduction due to hesitancy and other factors. Difficulty adhering to regular ingestion after introduction further reduces the effectiveness of primary prevention. As emerging real-world evidence has demonstrated that performing peanut oral immunotherapy (OIT) among infants is effective and safe, peanut OIT could be a treatment option for infants with peanut allergy. This review discusses the benefits, risks, and barriers to offering peanut OIT to infants who fail primary prevention strategies. We propose the novel concept that infants with peanut allergy be offered peanut OIT as soon as possible after failed peanut introduction through a shared decision-making process with the family, where there is a preference for active management rather than avoidance.

Patient selection for milk and egg ladders using a food ladder safety checklist

A food ladder is a form of home-based dietary advancement therapy that gradually increases exposure to an allergenic food through the gradual introduction of egg or milk containing food with increasing quantity and allergenicity from extensively heated forms, such as baked goods, to less processed products. While widely considered safe, the food ladder is not risk-free and most of the egg and milk ladder studies only included preschoolers with mild egg and milk allergies, and with no or well-controlled asthma. We propose a Food Ladder Safety Checklist to assist with patient selection using “4 A's” based on available evidence for food ladders, including Age, active or poorly controlled Asthma, history of Anaphylaxis, and Adherence.

Diverse clinical features and diagnostic delay in monogenic inborn errors of immunity: A call for access to genetic testing

BACKGROUND

Inborn errors of immunity (IEIs) are a group of conditions affecting immune system development and function. Due to their clinical heterogeneity and lack of provider awareness, patients suffer from long diagnostic delays that increase morbidity and mortality. Next-generation sequencing facilitates earlier diagnosis and treatment of IEIs, but too often patients are unable to see the benefit of this technology due to gaps in providers' knowledge regarding which patients to test and barriers to accessing sequencing.

METHODS

Here, we provide detailed clinical phenotyping and describe the impact of genetic sequencing on a cohort of 43 patients with monogenic IEIs seen in a tertiary care center from 2014 to 2019. Data were abstracted from a chart review, and a panel of clinical immunologists were consulted on the impact of genetic sequencing on their patients.

RESULTS

We found that our patients had significant diagnostic delays, averaging 3.3 years; had diverse manifestations of immune system dysfunction; and had demonstrated highly complex medical needs, with on average 7.9 subspecialties involved in their care and 4.9 hospitalizations prior to definitive treatment. Our results also demonstrate the benefits of genetic testing, as it provided the majority of our patients with a diagnosis, and positively impacted their treatment, follow-up, and prognosis.

CONCLUSION

This paper expands the paucity of literature on genetically confirmed IEIs in North America and supports the expansion of access to genetic testing for patients with clinical features suggesting IEI, such as those presented in our cohort.

Allergic reactions to emerging food allergens in Canadian children

Most Canadian food allergy data has focused on Health Canada’s priority food allergens. This study describes which non-priority (emerging) food allergens were most commonly reported by Canadian parents and categorized/confirmed by allergists. A secondary aim was to describe severity of allergic reactions to emerging allergens. Parents reported allergic reactions to emerging food allergens experienced by their child (< 18 years) which occurred in the past 12 months, and allergists categorized/confirmed them according to likelihood of IgE-mediated food allergy. Of 68 eligible patients completing the survey, the most commonly reported emerging allergens were fruits/vegetables (58.8%), seeds (22.1%), legumes (19.1%) and other (11.8%). Median allergist ranking for legumes was ‘probable’ IgE-mediated food allergy, ‘possible’ for seeds and fruits/vegetables, and ‘unlikely’ for other. Median reaction severity was mild for legumes, and moderate for seeds, fruits/vegetables, and other. Our study highlights that non-priority food allergens, namely legumes and seeds, can lead to probable/likely allergic reactions in Canadian children. These food allergens are increasing in popularity in the Canadian diet, which could lead to increasing reports of allergic reactions. More research is needed to confirm reports of reactions to emerging allergens, and to document their inclusion as ingredients in packaged foods.

First Real-World Effectiveness Analysis of Preschool Peanut Oral Immunotherapy

BACKGROUND

We previously described safety of preschool peanut oral immunotherapy (P-OIT) in a real-world setting; 0.4% of patients experienced a severe reaction, and 4.1% received epinephrine, during build-up.

OBJECTIVE

To determine the effectiveness of preschool P-OIT after 1 year of maintenance.

METHODS

Preschoolers (9-70 months) with at least 1 objective reaction to peanut (during baseline oral food challenge (OFC) or P-OIT build-up) received a follow-up OFC to cumulative 4000 mg protein after 1 year on 300 mg peanut daily maintenance. Effectiveness of desensitization was defined as proportion of patients with a negative follow-up OFC. Symptoms and treatment at follow-up OFC were recorded.

RESULTS

Of the 117 patients who successfully completed 1 year of P-OIT and subsequently underwent a cumulative 4000-mg follow-up OFC, 92 (78.6%) had a negative OFC and 115 (98.3%) tolerated a cumulative dose of greater than or equal to 1000 mg. For the 25 (21.4%) who reacted, their threshold increased by 3376 mg (95% CI, 2884-3868) from baseline to follow-up; 17 (14.5%) patients experienced grade 1 reactions, 7 (6.00%) grade 2, and 1 (0.85%) grade 3. Two patients (1.71%) received epinephrine associated with P-OIT, and 1 (0.85%) went to the emergency department.

CONCLUSIONS

Our data demonstrate that real-world preschool P-OIT is effective after 1 year of maintenance for those who received a follow-up OFC. For those who reacted, their threshold increased sufficiently to protect against accidental exposures. P-OIT should be considered for preschoolers as an alternative to current recommendations to avoid peanut.

STIM1-mediated calcium influx controls antifungal immunity and the metabolic function of non-pathogenic Th17 cells

Immunity to fungal infections is mediated by cells of the innate and adaptive immune system including Th17 cells. Ca²⁺ influx in immune cells is regulated by stromal interaction molecule 1 (STIM1) and its activation of the Ca²⁺ channel ORAI1. We here identify patients with a novel mutation in STIM1 (p.L374P) that abolished Ca²⁺ influx and resulted in increased susceptibility to fungal and other infections. In mice, deletion of STIM1 in all immune cells enhanced susceptibility to mucosal C. albicans infection, whereas T cell‐specific deletion of STIM1 impaired immunity to systemic C. albicans infection. STIM1 deletion impaired the production of Th17 cytokines essential for antifungal immunity and compromised the expression of genes in several metabolic pathways including Foxo and HIF1α signaling that regulate glycolysis and oxidative phosphorylation (OXPHOS). Our study further revealed distinct roles of STIM1 in regulating transcription and metabolic programs in non‐pathogenic Th17 cells compared to pathogenic, proinflammatory Th17 cells, a finding that may potentially be exploited for the treatment of Th17 cell‐mediated inflammatory diseases.

Recurrent sterile abscesses in a case of X-linked neutropenia

Cutaneous manifestations are common in monogenic immune disorders, including both infectious and non-infectious etiologies. We report follow-up of a case initially published in Pediatric Dermatology in 2001 of a 13-year-old boy with a history of inflammatory skin lesions and neutropenia who developed neutrophilic dermatoses precipitated by G-CSF. Whole exome sequencing performed at 36 years of age revealed a gain-of-function mutation in the WAS gene, leading to a diagnosis of X-linked neutropenia. This case report provides closure on a decades-long diagnostic odyssey and underscores the importance of genetic sequencing in patients who present with unusual dermatologic findings.

Parents of children with food allergy: A qualitative study describing needs and identifying solutions

BACKGROUND

Parents experience a wide range of emotions, specifically stress and anxiety, when their child receives a diagnosis of a food allergy. Managing this health condition and coping with emotions require professional and peer support. Currently, there is a lack of resources and a lack of awareness of the resources that are required to help assist parents in managing their child's food allergy.

OBJECTIVE

To describe parental experiences when caring for a child with food allergy and to review the resources parents need to manage living with a child with food allergy and more specifically how they would want these resources delivered.

METHODS

A total of 7 semistructured focus groups were conducted in British Columbia, Canada. Parents were asked to describe their experiences with managing their child's food allergy and identify helpful resources.

RESULTS

A total of 40 parents (33 females) participated in the focus groups. Participant demographics were collected. The following 3 main themes emerged: (1) anxiety (an emotional roller coaster); (2) a transformational journey (the waiting game, loss of normalcy, strained relationships and mistrust, and financial challenges); and (3) the need for resources (day to day management, ages and stages, mental health supports, and "the dream").

CONCLUSION

An in-person allied health care team is needed to provide an integrated, patient-centered approach for how families can live and manage food allergies. Credible information and resources, such as medically reviewed websites, support groups, and counseling services, with a goal of reducing child and parental anxiety, should be provided by health care professionals.

CSACI guidelines for the ethical, evidence-based and patient-oriented clinical practice of oral immunotherapy in IgE-mediated food allergy

Background

Oral immunotherapy (OIT) is an emerging approach to the treatment of patients with IgE-mediated food allergy and is in the process of transitioning to clinical practice.

Objective

To develop patient-oriented clinical practice guidelines on oral immunotherapy based on evidence and ethical imperatives for the provision of safe and efficient food allergy management.

Materials and methods

Recommendations were developed using a reflective patient-centered multicriteria approach including 22 criteria organized in five dimensions (clinical, populational, economic, organizational and sociopolitical). Data was obtained from: (1) a review of scientific and ethic literature; (2) consultations of allergists, other healthcare professionals (pediatricians, family physicians, nurses, registered dieticians, psychologists, peer supporters), patients and caregivers; and patient associations through structured consultative panels, interviews and on-line questionnaire; and (3) organizational and economic data from the milieu of care. All data was synthesized by criteria in a multicriteria deliberative guide that served as a platform for structured discussion and development of recommendations for each dimension, based on evidence, ethical imperatives and other considerations.

Results

The deliberative grid included 162 articles from the literature and media reviews and data from consultations involving 85 individuals. Thirty-eight (38) recommendations were made for the practice of oral immunotherapy for the treatment of IgE mediated food allergy, based on evidence and a diversity of ethical imperatives. All recommendations were aimed at fostering a context conducive to achieving objectives identified by patients and caregivers with food allergy. Notably, specific recommendations were developed to promote a culture of shared responsibility between patients and healthcare system, equity in access, patient empowerment, shared decision making and personalization of OIT protocols to reflect patients' needs. It also provides recommendations to optimize organization of care to generate capacity to meet demand according to patient choice, e.g. OIT or avoidance. These recommendations were made acknowledging the necessity of ensuring sustainability of the clinical offer in light of various economic considerations.

Conclusions

This innovative CPG methodology was guided by patients' perspectives, clinical evidence as well as ethical and other rationales. This allowed for the creation of a broad set of recommendations that chart optimal clinical practice and define the conditions required to bring about changes to food allergy care that will be sustainable, equitable and conducive to the well-being of all patients in need.

First Real-World Safety Analysis of Preschool Peanut Oral Immunotherapy

BACKGROUND

In 2017, a clinical trial of 37 subjects demonstrated that preschool peanut oral immunotherapy (P-OIT) was safe, with predominantly mild symptoms reported and only 1 moderate reaction requiring epinephrine.

OBJECTIVES

We sought to examine whether these findings would be applicable in a real-world setting.

METHODS

As part of a Canada-wide quality improvement project, community and academic allergists administered P-OIT to preschool-age children who had (1) skin prick test wheal diameter greater than or equal to 3 mm or specific IgE level greater than or equal to 0.35 kU/L and history of reaction and/or positive baseline oral food challenge, or (2) no ingestion history and specific IgE level greater than or equal to 5 kU/L. Over 16 to 22 weeks, patients had biweekly clinic visits for updosing, and consumed the dose daily at home between visits. Target maintenance dose was 300 mg peanut protein. Symptoms were classified using a modified World Allergy Organization Subcutaneous Immunotherapy Reaction Grading System (1 mildest, 5 fatal).

RESULTS

Of 270 patients who started P-OIT in the period 2017 to 2018, 243 reached maintenance, and 27 dropped out (10.0%); 67.8% of patients experienced reactions during buildup: 36.3% grade 1, 31.1% grade 2, and 0.40% grade 4. Eleven patients (4.10%) received epinephrine (10 patients received 1 dose, 1 patient received epinephrine on 2 separate days), representing 2.23% of reactions (12 of 538) and 0.029% of doses (12 of 41,020).

CONCLUSIONS

We are the first group to describe preschool P-OIT in a real-world multicenter setting. The treatment appears to be safe for the vast majority of patients because symptoms were generally mild and very few reactions received epinephrine; however, life-threatening reactions in a minority of patients (0.4%) can still occur.

T helper cell polarisation as a measure of the maturation of the immune response

BACKGROUND: T helper cell polarisation is important under chronic immune stimulatory conditions and drives the type of the evolving immune response. Mice treated with superantigens in vivo display strong effects on Th subset differentiation. The aim of the study was to detect the intrinsic capacity of T cells to polarise under various ex vivo conditions. METHODS: Purified CD4+ T cells obtained from super-antigen-treated mice were cultured under Th polarising conditions in vitro. By combining intracellular cytokine staining and subsequent flow cytometric analysis with quantitative cytokine measurements in culture supernatants by enzyme-linked immunosorbent assay (ELISA), the differential Th polarising capacity of the treatment can be detected in a qualitative and quantitative manner. RESULTS AND CONCLUSIONS: BALB/c mice were shown to be biased to develop strong Th2 polarised immune responses using Th0 stimulation of purified CD4+ T cells from phosphate-buffered saline-treated mice. Nevertheless, our analysis methodology convincingly showed that even in these mice, Toxic Shock Syndrome Toxin-1 treatment in vivo resulted in a significantly stronger Th1 polarising effect than control treatment. Our results indicate that populations of Th cells can be assessed individually for their differential Th1 or Th2 maturation capacity in vivo by analysing robust in vitro polarisation cultures combined with intracellular cytokine staining and ELISA.

Temporal sequence and functional implications of V beta-specific T cell receptor down-regulation and costimulatory molecule expression following in vitro stimulation with the staphylococcal superantigen Toxic shock syndrome toxin-1

The superantigen toxic shock syndrome toxin-1 (TSST-1) is implicated as the major cause of staphylococcal toxic shock syndrome. The temporal sequence of early signaling events in human peripheral blood mononuclear cells following TSST-1 stimulation was examined. TSST-1 induced rapid and complete down-regulation of V beta 2-specific T cell receptor (TCR), followed by transient CD154 expression on CD4(+) lymphocytes. This was sequentially followed by the up-regulation of CD86, CD80, CD40, and human leukocyte antigen-DR expression on CD14(+) monocytes. In contrast, S14N, a TSST-1 mutant toxin with a single amino acid substitution that is known to be impaired in interleukin (IL)--2, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha secretion, was deficient in both V beta 2-TCR down-regulation and CD154 and CD80/CD86 expression. Furthermore, pretreatment with monoclonal antibodies against V beta 2-TCR, CD80/CD86, and CD154 significantly inhibited TSST-1-induced IL-2, IFN-gamma, and TNF-alpha secretion. Taken together, these results indicate that early V beta-specific TCR activation, along with CD80/CD86 and CD154 costimulation, are key determinants of the TSST-1-induced proinflammatory cytokine response.

Temporal sequence and kinetics of proinflammatory and anti-inflammatory cytokine secretion induced by toxic shock syndrome toxin 1 in human peripheral blood mononuclear cells

The staphylococcal superantigen toxic shock syndrome toxin 1 (TSST-1) induces massive cytokine production, which is believed to be the key factor in the pathogenesis of TSS. The temporal sequence and kinetics of both proinflammatory and anti-inflammatory cytokines induced by TSST-1 in human peripheral blood mononuclear cells were investigated. A panel of loss-of-function single-amino-acid-substitution mutants of TSST-1, previously demonstrated to be defective in either major histocompatibility complex (MHC) class II binding (G31R) or T-cell receptor (TCR) interaction (H135A, S14N), was studied in parallel to further elucidate the mechanisms of cytokine secretion. Wild-type recombinant (WT r) TSST-1 induced a biphasic pattern of cytokine secretion: an early phase with rapid release of proinflammatory cytokines (especially gamma interferon, interleukin-2 [IL-2], and tumor necrosis factor alpha [TNF-alpha]) within 3 to 4 h poststimulation, and a later phase with more gradual production of both proinflammatory (IL-1beta, IL-12, and TNF-beta) and anti-inflammatory (IL-6, IL-10) cytokines within 16 to 72 h poststimulation. G31R, which is defective in MHC class II binding, induced a cytokine profile similar to that of WT rTSST-1, except that secretion of the early-phase proinflammatory cytokines was delayed and production of IL-1beta and IL-12 was markedly reduced. In contrast, mutant toxins defective in TCR interaction either demonstrated complete absence of any cytokine secretion during the entire observation period (H135A) or resulted in complete abolishment of IL-2 and other early-phase proinflammatory cytokines, while secretion of IL-10 appeared unaffected (S14N). Neither WT rTSST-1 nor the mutant toxins induced IL-4 or transforming growth factor beta. Our data indicate that effective TCR interaction is critical for the induction of the early-phase proinflammatory cytokine response, thus underscoring the importance of T-cell signaling in TSS.

Regulation of helper T cell responses to staphylococcal superantigens

Staphylococcal superantigens (sAgs) including toxic shock syndrome toxin-1 (TSST-1) and related enterotoxins are exoproteins with unique immunobiological properties. They bind to major histocompatibility complex (MHC) class II molecules of antigen-presenting cells outside the peptide groove, and induce massive proliferation of T cells bearing specific V beta determinants. This tri-molecular interaction leads to uncontrolled release of various proinflammatory cytokines especially interferon-gamma (IFN-gamma) and tumor necrosis factor-a (TNF-alpha), the key cytokines causing sAg-mediated shock. The effector T cells involved in this hyper-immune response are predominantly of the T helper-1 (Th1) phenotype. There is also some evidence that polarization to a Th2 response with the production of classical anti-inflammatory cytokines (such as interleukins IL-4 and IL-6) also occurs. Moreover, the emergence of a novel regulatory T cell (Tr1) subset, producing mainly IL-10 but little or no IL-2 and IL-4, has recently been described following repeated sAg stimulation. In this review, the current knowledge regarding the regulation of T helper cell subsets in response to staphylococcal sAgs is critically evaluated, and the role of various cytokines which directly influence T cell differentiation and polarization is summarized. Particular emphasis is directed towards pro-inflammatory as well as anti-inflammatory and regulatory effector functions during toxic shock. Based on this review, we propose that a delayed production of IL-10 by Tr1 cells may be the most prominent driving force in the down-regulation of the Th1 hyper-immune response, and the critical determinant for the eventual recovery of the host.

Stool carriage, clinical isolation, and mortality during an outbreak of vancomycin-resistant enterococci in hospitalized medical and/or surgical patients

During a nosocomial outbreak of infection due to vancomycin-resistant enterococci (VRE), rectal swabs that were collected weekly were used to identify and isolate VRE carriers. Over 6 months, 1,458 stool specimens from 724 high-risk patients were cultured, and 187 VRE isolates were recovered from 61 patients; 96% of the isolates were Enterococcus faecium. VRE tended to be isolated from clinical specimens from patients identified as VRE carriers by stool surveillance (P < .01). However, isolation of VRE from surveillance cultures preceded clinical isolation for only approximately 50% of the patients from whom a clinical VRE isolate was recovered. Mortality was greater (P < .05) among patients from whom a clinical VRE isolate was recovered than among patients from whom VRE was isolated only by stool surveillance. The mortality (1[17%] of 6) among patients for whom VRE was isolated from blood was similar to that (10 [27%] of 37) among patients for whom vancomycin-susceptible enterococcus was isolated from blood (P = .97). Despite prompt initiation of contact precautions for VRE carriers, the incidence of fecal carriage of VRE remained approximately 8% among this patient population for the 6-month period of the study.

Transmission of gram-negative bacilli to asthmatic children via home nebulizers

Home use of nebulizers has increased in recent years, although adequate studies have not been performed to evaluate for possible contamination or transmission of potentially harmful bacteria. This study of 20 asthmatic children demonstrated that transmission of pathogenic bacteria occurs.