Work Group Report: COVID-19: Unmasking Telemedicine

Telemedicine adoption has rapidly accelerated since the onset of the COVID-19 pandemic. Telemedicine provides increased access to medical care and helps to mitigate risk by conserving personal protective equipment and providing for social/physical distancing to continue to treat patients with a variety of allergic and immunologic conditions. During this time, many allergy and immunology clinicians have needed to adopt telemedicine expeditiously in their practices while studying the complex and variable issues surrounding its regulation and reimbursement. Some concerns have been temporarily alleviated since March 2020 to aid with patient care in the setting of COVID-19. Other changes are ongoing at the time of this publication. Members of the Telemedicine Work Group in the American Academy of Allergy, Asthma & Immunology (AAAAI) completed a telemedicine literature review of online and Pub Med resources through May 9, 2020, to detail Pre-COVID-19 telemedicine knowledge and outline up-to-date telemedicine material. This work group report was developed to provide guidance to allergy/immunology clinicians as they navigate the swiftly evolving telemedicine landscape.

Reducing Environmental Allergic Triggers: Policy Issues

The implementation of policies to reduce environmental allergic triggers can be an important adjunct to optimal patient care for allergic rhinitis and allergic asthma. Policies at the local level in schools and other public as well as private buildings can make an impact on disease morbidity. Occupational exposures for allergens have not yet been met with the same rigorous policy standards applied for exposures to toxicants by Occupational Safety and Health Administration. Further benefit may be obtained through policies by local, county, state, and national governments, and possibly through international cooperative agreements. The reduction of allergenic exposures can and should be affected by policies with strong scientific, evidence-based derivation. However, a judicious application of the precautionary principle may be needed in circumstances where the health effect of inaction could lead to more serious threats to vulnerable populations with allergic disease. This commentary covers the scientific basis, current implementation, knowledge gaps, and pro/con views on policy issues in reducing environmental allergic triggers.

Indoor Environmental Control Practices and Asthma Management

Indoor environmental exposures, particularly allergens and pollutants, are major contributors to asthma morbidity in children; environmental control practices aimed at reducing these exposures are an integral component of asthma management. Some individually tailored environmental control practices that have been shown to reduce asthma symptoms and exacerbations are similar in efficacy and cost to controller medications. As a part of developing tailored strategies regarding environmental control measures, an environmental history can be obtained to evaluate the key indoor environmental exposures that are known to trigger asthma symptoms and exacerbations, including both indoor pollutants and allergens. An environmental history includes questions regarding the presence of pets or pests or evidence of pests in the home, as well as knowledge regarding whether the climatic characteristics in the community favor dust mites. In addition, the history focuses on sources of indoor air pollution, including the presence of smokers who live in the home or care for children and the use of gas stoves and appliances in the home. Serum allergen-specific immunoglobulin E antibody tests can be performed or the patient can be referred for allergy skin testing to identify indoor allergens that are most likely to be clinically relevant. Environmental control strategies are tailored to each potentially relevant indoor exposure and are based on knowledge of the sources and underlying characteristics of the exposure. Strategies include source removal, source control, and mitigation strategies, such as high-efficiency particulate air purifiers and allergen-proof mattress and pillow encasements, as well as education, which can be delivered by primary care pediatricians, allergists, pediatric pulmonologists, other health care workers, or community health workers trained in asthma environmental control and asthma education.

Proteinases as molecular adjuvants in allergic airway disease

BACKGROUND

Asthma and related respiratory tract allergic diseases are among the most common chronic diseases of adults and children. Despite their importance, disease course cannot be predicted and treatment remains non-specific and potentially hazardous, with no means for cure. Improved clinical management of asthma will require an improved understanding of the fundamental factors that initiate allergic inflammation, especially T helper type 2 (T(H)2) cell induction.

SCOPE OF REVIEW

In this review, we explore the Proteinase Hypothesis of allergic airway disease, considering specifically how organismal proteinases contribute to the expression of allergic disease and potentially important proteinase signaling pathways.

MAJOR CONCLUSIONS

Proteinases from diverse sources (bacteria, fungi, plants) may cause occupational asthma by acting as immune adjuvant factors that specifically elicit T(H)2 cell-dependent allergic inflammation. However, more conventional allergic airway diseases (asthma, allergic sinusitis) are more likely to arise from contained fungal or viral infections of the airway in which proteinases are produced and serve as major virulence factors. Proteinases may elicit allergic disease by disrupting numerous cellular proteins, potentially including Toll like receptor (TLR) 4, but critical proteinase-activated signaling pathways remain largely unknown.

GENERAL SIGNIFICANCE

Clarification of how proteinases cause allergic disease, specifically confirming an infectious basis for airway proteinase exposure, will likely radically advance how asthma and related respiratory tract disorders are diagnosed and treated. This article is part of a Special Issue entitled Biochemistry of Asthma.

Vaccine-acquired rotavirus in infants with severe combined immunodeficiency

Live pentavalent human-bovine reassortant rotavirus vaccine is recommended in the United States for routine immunization of infants. We describe three infants, two with failure to thrive, who had dehydration and diarrhea within 1 month after their first or second rotavirus immunization and subsequently received a diagnosis of severe combined immunodeficiency. Rotavirus was detected, by means of reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, in stool specimens obtained from all three infants, and gene-sequence analysis revealed the presence of vaccine rotavirus. These infections raise concerns regarding the safety of rotavirus vaccine in severely immunocompromised patients.

Outcomes of patients with severe combined immunodeficiency treated with hematopoietic stem cell transplantation with and without preconditioning

BACKGROUND

The effect of pretransplantation conditioning on the long-term outcomes of patients receiving hematopoietic stem cell transplantation for severe combined immunodeficiency (SCID) has not been completely determined.

OBJECTIVE

We sought to assess the outcomes of 23 mostly conditioned patients with SCID and compare their outcomes with those of 25 previously reported nonconditioned patients with SCID who underwent transplantation.

METHODS

In the present study we reviewed the medical records of these 23 consecutive, mostly conditioned patients with SCID who underwent transplantation between 1998 and 2007.

RESULTS

Eighteen patients (median age at transplantation, 10 months; range, 0.8-108 months) received haploidentical mismatched related donor, matched unrelated donor, or mismatched unrelated donor transplants, 17 of whom received pretransplantation conditioning (with 1 not conditioned); 13 (72%) patients engrafted with donor cells and survive at a median of 3.8 years (range, 1.8-9.8 year); 5 (38%) of 13 patients require intravenous immunoglobulin; and 6 of 6 age-eligible children attend school. Of 5 recipients (median age at transplantation, 7 months; range, 2-23 months) of matched related donor transplants, all 5 engrafted and survive at a median of 7.5 years (range, 1.5-9.5 year), 1 recipient requires intravenous immunoglobulin, and 3 of 3 age-eligible children attend school. Gene mutations were known in 16 cases: mutation in the common gamma chain of the IL-2 receptor (IL2RG) in 7 patients, mutation in the alpha chain of the IL-7 receptor (IL7RA) in 4 patients, mutation in the recombinase-activating gene (RAG1) in 2 patients, adenosine deaminase deficiency (ADA) in 2 patients, and adenylate kinase 2 (AK2) in 1 patient. Early outcomes and quality of life of the previous nonconditioned versus the present conditioned cohorts were not statistically different, but longer-term follow-up is necessary for confirmation.

CONCLUSIONS

Hematopoietic stem cell transplantation in patients with SCID results in engraftment, long-term survival, and a good quality of life for the majority of patients with or without pretransplantation conditioning.

Hemophagocytic lymphohistiocytosis in a patient with x-linked lymphoproliferative disease

X-linked lymphoproliferative disease (XLP) is a primary immunodeficiency affecting approximately 1 to 3 per million live male births. Patients are generally healthy until facing a viral infection such as Epstein-Barr Virus and then may develop fulminant infectious mononucleosis and die. XLP patients are also at increased risk of hemophagocytic lymphohistiocytosis (HLH), which may be triggered by assorted viruses. Here we report a novel case of HLH in a patient with XLP. Significant to his presentation is a paradoxical increase in natural killer (NK) cell activity. We hypothesize that this indicates that Parvovirus B19 activates NK cells via a signaling lymphocytic activation molecule-associated protein (SAP)-independent mechanism. Our case demonstrates an important etiology to consider in the differential diagnosis of XLP patients with nonfocal findings and febrile illnesses.

Long-term outcomes of nonconditioned patients with severe combined immunodeficiency transplanted with HLA-identical or haploidentical bone marrow depleted of T cells with anti-CD6 mAb

BACKGROUND

Between 1981 and 1995, 20 children with severe combined immunodeficiency (SCID; median age at transplant, 6.5 [range, 0.5-145] mo, 12 with serious infection) were treated with haploidentical T cell-depleted (anti-CD6 antibody) bone marrow (median number of 5.7 [0.8-18.8] x 10(8) nucleated cells/kg) from mismatched related donors (MMRDs), and 5 children with SCID (median age at transplant, 1.8 [0.5-5.0] mo, 1 with serious infection) were given unmanipulated bone marrow from matched related donors (MRDs). No conditioning or graft-versus-host disease (GvHD) prophylaxis was used.

OBJECTIVE

To assess the outcomes of patients with SCID who received bone marrow from MMRDs or MRDs.

METHODS

We reviewed the medical records of these 25 consecutive patients with SCID (4 with Omenn syndrome).

RESULTS

Of the 20 patients who received bone marrow from MMRDs, 12 engrafted, 10 survived at a median age of 15.2 [10.0-19.1] years, 4 had chronic GvHD (lung, intestine, skin), 5 required intravenous immunoglobulin, and 8 attended school or college. Two of 5 patients who died had chronic GvHD, and 2 developed lymphoproliferative disease. Of the 5 patients who received bone marrow from MRDs, 5 engrafted, 5 survived at a median age of 23.3 [18.5-26] years, 1 had chronic GvHD (lung, skin), 2 required intravenous immunoglobulin, and 4 attended school or college.

CONCLUSIONS

Treatment of critically ill patients with SCID with anti-CD6 antibody T cell-depleted MMRD marrow resulted in an overall 50% long-term survival of patients (83% survival of those engrafted). The principal barriers to long-term survival were delay in diagnosis, life-threatening infection, failure to engraft, and chronic GvHD. Educational goals were achieved in most of the survivors.

Computer-based decision support for pediatric asthma management: description and feasibility of the Stop Asthma Clinical System

Clinical guidelines can assist in the management of asthma. Decision support systems (DSSs) can enhance adherence to clinical guidelines but tend not to provide clinicians with cues for behavioral change strategies to promote patient self-management. The Stop Asthma Clinical System (SACS) is a DSS designed for this purpose. To assess feasibility, seven clinicians used SACS to guide well visits with 26 predominantly persistent pediatric asthma patients. Data were collected via survey and in-depth semi-structured interviews. SACS improved assessment of asthma severity and control, classification of and intervention in medicine and environmental trigger management problems, and development of an action plan (all p < 0.05). Clinician-patient communication was enhanced. The primary challenge was that SACS increased clinic visit time. SACS can enhance clinician behavior to improve patient asthma self-management, but more studies are indicated to mitigate temporal constraints and evaluate impact on clinician and patient communication and behavior as well as clinical outcomes.

Partners in school asthma management: evaluation of a self-management program for children with asthma

The "Partners in School Asthma Management" program for inner-city elementary school children comprises (1) case finding; (2) linkage of school nurses, parents, and clinicians; (3) a computer-based tailored educational program; and (4) school environmental assessment and intervention. Case finding identified 1730 children in 60 elementary schools with probable asthma; 835 (96% Hispanic or African American) joined the study. Baseline, posttest, and follow-up measures of asthma knowledge, self-efficacy, and self-management behavior were obtained from the children, and data on symptoms, emergency department visits, and hospitalizations were obtained from their parents. The schools provided data on grades and absences. Each school had a baseline and follow-up environmental assessment. The children in the intervention group showed greater increases in knowledge, self-efficacy, and some aspects of self-management. No differences between groups were found in health status variables, school performance, attendance, or levels of environmental allergens in schools. In 15 schools, an enhanced intervention allowed children and their parents to meet with a project physician, develop an asthma action plan, and receive a 1-month supply of medication; the project physician then followed up with the child's community physician. Children participating in this enhanced intervention had better school performance and fewer absences than the comparison group. Overall, the program was effective in improving children's asthma self-management but not in improving their health status. While the case-finding, computer-based self-management training program and linkage system were successfully implemented, the program failed in creating needed changes in the medical (action plans by community physicians) and physical environments (reduced school allergen levels) of the children.

Allergens in school settings: results of environmental assessments in 3 city school systems

Environmental allergens are major triggers for pediatric asthma. While children's greatest exposure to indoor allergens is in the home, other public places where children spend a large amount of time, such as school and day care centers, may also be sources of significant allergen encounters. The purpose of this article is to describe schoolroom allergen levels from 3 different geographic sites obtained from dust samples collected in the fall and in spring. Environmental dust samples were collected from elementary schools in Birmingham (AL), Detroit (MI), and Houston (TX), from 4 room locations, including the cafeteria, library, upper grades, and lower grades. Samples were assayed for dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cat (Felis domesticus), and cockroach (Blatella germanica 2) allergen levels. Allergen levels varied by geographic location and type of schoolroom. Schoolroom settings differed by the type of flooring (hard and carpet), room characteristics and use (food service, library shelves with books, and general classroom with multiple types of materials [individual desks and different types of furniture]), and the average age of the schoolroom dwellers (younger vs. older children). Dust mite, cat, and cockroach allergens were present in all schoolrooms and all sites at varying levels by season and by type of room. Schools may be important sources of direct allergen exposure and reservoirs that could potentially contribute to allergic sensitization and disease exacerbation in children. Further studies are needed to carefully examine the environmental allergen load in schools and its effect on children.

Development of an expert system knowledge base: a novel approach to promote guideline congruent asthma care

Existing guidelines for the clinical management of asthma provide a good framework for such tasks as diagnosing asthma, determining severity, and prescribing pharmacological treatment. Guidance is less explicit, however, about establishing a patient-provider partnership and overcoming barriers to asthma management by patients in a way that can be easily adopted in clinical practice. We report herein the first developmental phase of the "Stop Asthma" expert system. We describe the establishment of a knowledge base related to both the clinical management of asthma and the enhancement of patient and family self-management (including environmental management). The resultant knowledge base comprises 142 multilayered decision rules that describe clinical and behavioral management in three domains: 1) determination of asthma severity and control; 2) pharmacotherapy, including prescription of medicine for chronic maintenance, acute exacerbation, exercise pretreatment, and rhinitis relief; and 3) patient self-management, including the process of intervening to facilitate the patient's asthma medication management, environmental control, and well-visit scheduling. The knowledge base provides a systematic and accessible approach for intervening with family asthma-related behaviors.

A 5-week-old HIV-1–exposed girl with failure to thrive and diffuse nodular pulmonary infiltrates

A 5-week-old female infant with vertical HIV-1 exposure, progressive cough, and failure to thrive was given a diagnosis of bilateral diffuse nodular lung lesions. The child was without fever, leukocytosis, anemia, peripheral adenopathy, or hepatosplenomegaly, and the results of repeated blood tests for HIV-1 DNA were negative. A needle biopsy of the lungs revealed granulomatous inflammation and giant cells, with fungal organisms suggestive of Aspergillus species. A nitroblue tetrazolium dye test performed on the patient's blood specimen demonstrated absence of dye reduction, suggesting a diagnosis of chronic granulomatous disease. Further analysis revealed that the child had a deficiency of the p47(phox) component of the nicotinamide adenine dinucleotide phosphate oxidase system. Thus this child with vertical HIV-1 exposure and diffuse pulmonary nodules actually had an autosomal recessive form of chronic granulomatous disease. This case study clearly demonstrates that children with suspected HIV-1 infection might also need evaluation for primary immunodeficiency and that the clinical immunology laboratory is a powerful adjunct in coming to a correct diagnosis.

Environmental allergens and irritants in schools: a focus on asthma

As part of the Partners in School Asthma Management Program, environmental data were collected from 385 rooms in 60 elementary schools in southeast Texas, using an Environmental Observation Checklist and a Q-TRAK Indoor Air Quality Monitor. Dust samples for allergen analysis were collected from floors, carpets, and area rugs in 80 classrooms in a subset of 20 schools. CO2 levels > 1,000 ppm were found in 86% of rooms; 69% had indoor humidity above recommended levels. Der p I dust mite allergen levels > 2,000 ng/g were present in 20% of rooms, but only 2.5% of rooms had Der f I mite allergen levels exceeding recommended tolerances. Detectable levels of cockroach allergen (Bla g II) were found in all schools (median 5.5 ng/g), with 10% of rooms over the recommended threshold. Almost two-thirds of classrooms had mold spore counts > 10,000 col/g (median, 14,400 col/g; range, 2,000-52,000 col/g).

Impact of a computer-assisted education program on factors related to asthma self-management behavior

OBJECTIVE

To evaluate Watch, Discover, Think and Act (WDTA), a theory-based application of CD-ROM educational technology for pediatric asthma self-management education.

DESIGN

A prospective pretest posttest randomized intervention trial was used to assess the motivational appeal of the computer-assisted instructional program and evaluate the impact of the program in eliciting change in knowledge, self-efficacy, and attributions of children with asthma. Subjects were recruited from large urban asthma clinics, community clinics, and schools. Seventy-six children 9 to 13 years old were recruited for the evaluation.

RESULTS

Repeated-measures analysis of covariance showed that knowledge scores increased significantly for both groups, but no between-group differences were found (P: = 0.55); children using the program scored significantly higher (P: < 0.01) on questions about steps of self-regulation, prevention strategies, and treatment strategies. These children also demonstrated greater self-efficacy (P: < 0.05) and more efficacy building attribution classification of asthma self-management behaviors (P: < 0.05) than those children who did not use the program.

CONCLUSION

The WDTA is an intrinsically motivating educational program that has the ability to effect determinants of asthma self-management behavior in 9- to 13-year-old children with asthma. This, coupled with its reported effectiveness in enhancing patient outcomes in clinical settings, indicates that this program has application in pediatric asthma education.

Recombinant human gamma interferon in human immunodeficiency virus-infected children: safety, CD4(+)-lymphocyte count, viral load, and neutrophil function (AIDS Clinical Trials Group Protocol 211)

Nineteen children with human immunodeficiency virus (HIV) infection were treated with recombinant human gamma interferon (rIFN-gamma) (50 microg/m2 subcutaneously three times each week during weeks 1 through 12 and 100 microg/m2 subcutaneously three times each week during weeks 13 through 24) in a phase I/II clinical trial. All children continued to receive previously prescribed therapy with oral zidovudine or didanosine. Children were assessed clinically and with laboratory studies during 24 weeks of study treatment and for 12 weeks after completion of rIFN-gamma therapy. In general, rIFN-gamma therapy was well tolerated. There were two clinical or laboratory adverse events thought to be possibly or probably study drug associated. One child developed acute pancreatitis; another child developed granulocytopenia. Median CD4(+)-lymphocyte counts and plasma HIV RNA concentrations did not change significantly during therapy. In vitro neutrophil bactericidal activity against Staphylococcus aureus and superoxide production were not significantly affected by rIFN-gamma therapy. We conclude that rIFN-gamma therapy in HIV-infected children receiving single-agent antiretroviral therapy is safe and does not produce consistent changes in CD4(+)-lymphocyte count, plasma HIV RNA concentration, or in vitro neutrophil function.

Objective measures of allergic disease in children with human immunodeficiency virus infection

BACKGROUND

Available information suggests that IgE levels are elevated in adults infected with human immunodeficiency virus (HIV), and that increased IgE levels correlate with allergic disease, with decreased CD4 counts, and with a poor prognosis. Data with respect to these factors in children are scant.

OBJECTIVE

We investigated whether serum IgE levels are elevated in children with HIV and, if so, whether the serum IgE level correlates with the degree of immunodeficiency and/or objective indicators of allergic disease.

METHODS

Serum IgE levels, CD4 counts, absolute eosinophil counts, and immediate hypersensitivity skin test (IHST) results were collected from 43 children with symptomatic HIV infection (mean age 7.2 years). Associations between serum IgE levels, CD4 counts, and eosinophil counts were investigated by multiple stepwise linear regression analysis. Data were stratified according to IHST positivity, and analysis of variance was used to compare mean values for age, CD4 counts, IgE levels, and eosinophil counts between the two groups.

RESULTS

Serum IgE values were elevated more than 2 SDs above control age-matched mean values in 17 of 43 patients (40%). IHST results were positive in 12 of 43 patients (28%). CD4 counts were less than 200/mm3 in 17 of 43 patients (40%). Stepwise linear regression failed to demonstrate any correlation between serum IgE levels and either CD4 or eosinophil counts. With data divided into two groups according to IHST results (positive vs negative), analysis of variance failed to reveal significant differences between means for patient age, CD4 counts, IgE levels, or eosinophil counts.

CONCLUSIONS

Our findings confirm that serum IgE levels are increased in children infected with HIV, just as in adults. However, an elevated serum IgE level did not correlate with allergic disease as measured by IHST results and eosinophil counts, nor with the degree of immune dysfunction as approximated by CD4 counts. The mechanism and significance of elevated serum IgE levels remain unclear in children with HIV, and warrant further investigation.

The surgical implications of chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease (CGD) of childhood is a rare congenital abnormality of the phagocyte NADPH oxidase system. Affected neutrophils and macrophages have an ineffective respiratory burst and cannot destroy certain phagocytized bacteria and fungi. CGD patients usually present with recurrent pyogenic and fungal infections. Catalase-positive bacteria are frequently involved, since they metabolize the hydrogen peroxide they produce, making it unavailable for augmentation of microbicidal activity in CGD neutrophils. Afflicted patients also have a tendency to form granulomas, which can lead to obstruction of the gastrointestinal and genitourinary tracts.

METHODS

Charts of 10 patients with CGD were reviewed for age at diagnosis, surgical procedures, complications of these procedures, and medical treatment.

RESULTS

Eight of the 10 children were male. The average age at first presentation was 18 months (range 2 days to 9.8 years). Each child developed a mean of 9.9 infections and an average of 1.4 infections per year. All required surgical procedures, with an average of 2.9 procedures each. Five children had operative procedures for infections that preceded the diagnosis of CGD. The procedures performed most frequently were incision and drainage of soft-tissue abcesses (7) or perirectal abscess (3), thoracentesis (3), and bronchoscopy (3). Three children had poor wound healing following surgery. Two developed partial gastric outlet obstruction which resolved with antibiotic therapy. One developed granulomatous cystitis with obstruction which responded to antibiotics.

CONCLUSIONS

Since patients with undiagnosed CGD may present with surgical problems, surgeons need to be familiar with this condition. The diagnosis should be suspected in children who have recurrent or unusual infections or unexplained problems with wound healing.

Ascorbic acid enhances iron-induced ferritin translation in human leukemia and hepatoma cells

Ascorbate is an important cofactor in many cellular metabolic reactions and is intimately linked to iron homeostasis. Continuously cultured cells are ascorbate deficient due to the lability of the vitamin in solution and to the fact that daily supplementation of media with ascorbate is unusual. We found that ascorbate repletion alone did not alter ferritin synthesis. However, ascorbate-replete human hepatoma cells, Hep3B and HepG2, as well as K562 human leukemia cells achieved a substantially higher cellular ferritin content in response to a challenge with iron than did their ascorbate-deficient counterparts grown under standard culture conditions. Most of the elevation in ferritin content was due to an increase in de novo ferritin synthesis of greater than 50-fold, as shown by in vivo labeling with [35S]methionine and immunoprecipitation. RNA-blot analysis showed only minor changes in steady state levels of ferritin mRNA, suggesting that ascorbate enhances iron-induced ferritin synthesis primarily by post-transcriptional events. Transient gene expression experiments using chloramphenicol acetyltransferase reporter gene constructs showed that the ascorbate effect on ferritin translation is not mediated through the stem-loop near the translational start site that transduces ferritin synthesis in response to cytokines. The data suggest that ascorbate possibly modifies the action of the iron-responsive element on ferritin translation, although more precise structure-function studies are needed to clarify this issue. These data demonstrate a novel role of ascorbate as a signaling molecule in post-transcriptional gene regulation. The mechanism by which ascorbate modulates cellular iron metabolism is complex and requires additional detailed investigation.

IL-4 inhibits superoxide production by human mononuclear phagocytes

The activation of mononuclear phagocytes (M phi) and their generation of oxidative products is influenced by various cytokines as well as by normal maturational changes. We examined the effects of IL-4 on superoxide (O2-) production (cytochrome c reduction) by cultured M phi and the modulation of these effects by IFN-gamma and IL-1. Incubation of IL-4 (200 U/ml) with M phi inhibited M phi PMA (100 ng/ml)-stimulated O2-. production by 23% at 24 h, 34% at 48 h, and 70 to 85% at 72 to 96 h. IL-4 similarly inhibited M phi O2-. production in response to zymosan. IL-4 did not affect M phi viability, adherence to microtiter plates, or ability to phagocytose boiled yeast. In comparison with M phi, neutrophil O2-. production was not inhibited after 4 to 20 h incubation with IL-4. When IL-4 was washed out as early as 1 h after the initiation of M phi culture, significant inhibition of O2-. production was observed 4 days later. Sequential addition of either IL-4 or IFN-gamma to cultures demonstrated reciprocal cytokine effects on M phi; IL-4 partially inhibited O2-. production by M phi previously treated with rIFN-gamma whereas rIFN-gamma partially augmented O2-. production by M phi previously treated with IL-4. Because IL-4 has been reported to inhibit IL-1 production, add-back experiments were performed; addition of IL-1 only partly reconstituted O2-. production in IL-4-treated cells. Further characterization showed that although M phi protein synthesis was enhanced by both rIFN-gamma and IL-4 treatment, acid phosphatase, a marker of maturation to the macrophage phenotype, was markedly increased at an earlier time point in IL-4-treated M phi, and correlated with a decline in O2-. production. The ability of IL-4 to suppress M phi O2-. production implicates IL-4 as an important regulator of this aspect of the inflammatory response.

IL-4 inhibits superoxide production by human mononuclear phagocytes

The activation of mononuclear phagocytes (M phi) and their generation of oxidative products is influenced by various cytokines as well as by normal maturational changes. We examined the effects of IL-4 on superoxide (O2-) production (cytochrome c reduction) by cultured M phi and the modulation of these effects by IFN-gamma and IL-1. Incubation of IL-4 (200 U/ml) with M phi inhibited M phi PMA (100 ng/ml)-stimulated O2-. production by 23% at 24 h, 34% at 48 h, and 70 to 85% at 72 to 96 h. IL-4 similarly inhibited M phi O2-. production in response to zymosan. IL-4 did not affect M phi viability, adherence to microtiter plates, or ability to phagocytose boiled yeast. In comparison with M phi, neutrophil O2-. production was not inhibited after 4 to 20 h incubation with IL-4. When IL-4 was washed out as early as 1 h after the initiation of M phi culture, significant inhibition of O2-. production was observed 4 days later. Sequential addition of either IL-4 or IFN-gamma to cultures demonstrated reciprocal cytokine effects on M phi; IL-4 partially inhibited O2-. production by M phi previously treated with rIFN-gamma whereas rIFN-gamma partially augmented O2-. production by M phi previously treated with IL-4. Because IL-4 has been reported to inhibit IL-1 production, add-back experiments were performed; addition of IL-1 only partly reconstituted O2-. production in IL-4-treated cells. Further characterization showed that although M phi protein synthesis was enhanced by both rIFN-gamma and IL-4 treatment, acid phosphatase, a marker of maturation to the macrophage phenotype, was markedly increased at an earlier time point in IL-4-treated M phi, and correlated with a decline in O2-. production. The ability of IL-4 to suppress M phi O2-. production implicates IL-4 as an important regulator of this aspect of the inflammatory response.

Regulation of immunoglobulin production in hyperimmunoglobulin E recurrent-infection syndrome by interferon gamma

The hyperimmunoglobulin E recurrent-infection (Job) syndrome (HIE) is a congenital disorder characterized by high serum IgE, chronic eczematoid dermatitis, and recurrent infections. We examined the effect of interferon gamma (IFN-gamma) on excessive IgE production in HIE patients. Spontaneous in vitro production of IgE by peripheral blood mononuclear cells from HIE patients was elevated compared to normal individuals and correlated with serum IgE. In 9 of 13 patients, IgE production by peripheral blood mononuclear cells was inhibited by 50% by IFN-gamma at 100-1000 units/ml, whereas inhibition by IFN-gamma at 10(4) units/ml ranged from 67 to 93% for these 9 patients. IFN-gamma also inhibited IgG1, IgG3, and IgG4 production by B lymphocytes without inhibiting IgG2 production. IFN-gamma was administered subcutaneously to 5 HIE patients. After 2 weeks of treatment with IFN-gamma (0.05 mg/m2) at three doses per week given on alternate days, peripheral blood mononuclear cells from all 5 HIE patients decreased spontaneous in vitro IgE production (27-62% decrease) with no change in IgG and IgM. One patient had a 58% decrease in serum IgE and another patient had a 50% decrease in serum IgE after the IFN-gamma was increased to 0.1 mg/m2 for three doses per week for a month. In both patients, serum IgE returned to pre-IFN-gamma-challenge levels 1-3 months after completion of treatment, and in vivo IFN-gamma did not affect serum IgG and IgM, although serum IgG4 decreased with changes in serum IgE. Our studies demonstrate that IFN-gamma can regulate production of IgE and some IgG subclasses in humans.

Cellular requirements for induction of human primary proliferative responses to trinitrophenyl-modified cells

Cellular requirements for induction of primary proliferative responses by human T cells to trinitrophenylated autologous stimulators have been characterized. Substantial proliferative responses were observed with each of the Ia+ stimulator populations tested. Nevertheless, major differences in the hapten specificity of such responses were observed. Thus purified macrophages/monocytes (M phi) when TNP-modified induced responses that were relatively modest in absolute magnitude, but were highly hapten specific. This reflected the very limited capacity of purified M phi to induce proliferation when unmodified, i.e., an autologous mixed leukocyte response (AMLR). In contrast, unmodified M phi-depleted B plus null cells were potent stimulators of AMLR, but hapten modification did not significantly enhance the responses induced by these cells. Moreover, when M phi were added to B plus null cell stimulators AMLR responses were reduced and, with TNP-modified stimulators, hapten-specific responses were restored. The data thus suggest that M phi may have important roles in induction of primary T cell responses to conventional antigens but function largely as regulators rather than stimulators of AMLR. Finally, we have introduced a novel antigen-presenting cell population, the irradiated Ia+ TNP-specific cloned T cell. The possibility that such cells may utilize autostimulatory positive feedback circuits for activation of naive T cells and in interactions between subpopulations of hapten-reactive T cells is discussed.

Cellular requirements for induction of human primary proliferative responses to trinitrophenyl-modified cells

Cellular requirements for induction of primary proliferative responses by human T cells to trinitrophenylated autologous stimulators have been characterized. Substantial proliferative responses were observed with each of the Ia+ stimulator populations tested. Nevertheless, major differences in the hapten specificity of such responses were observed. Thus purified macrophages/monocytes (M phi) when TNP-modified induced responses that were relatively modest in absolute magnitude, but were highly hapten specific. This reflected the very limited capacity of purified M phi to induce proliferation when unmodified, i.e., an autologous mixed leukocyte response (AMLR). In contrast, unmodified M phi-depleted B plus null cells were potent stimulators of AMLR, but hapten modification did not significantly enhance the responses induced by these cells. Moreover, when M phi were added to B plus null cell stimulators AMLR responses were reduced and, with TNP-modified stimulators, hapten-specific responses were restored. The data thus suggest that M phi may have important roles in induction of primary T cell responses to conventional antigens but function largely as regulators rather than stimulators of AMLR. Finally, we have introduced a novel antigen-presenting cell population, the irradiated Ia+ TNP-specific cloned T cell. The possibility that such cells may utilize autostimulatory positive feedback circuits for activation of naive T cells and in interactions between subpopulations of hapten-reactive T cells is discussed.

Antigen presentation to human T lymphocytes. II. Requirements for Mac-120+ macrophages and responsiveness to interleukin 2

To investigate mechanisms by which antigen, macrophages, and interleukin 2 (IL2) participate in the induction of secondary T-cell proliferative responses, trinitrophenyl (TNP) was presented in three distinct modes: (i) TNP-modified peripheral blood mononuclear cells (TNP-PBMC), (ii) TNP-PBMC cell sonicates, and (iii) TNP-ovalbumin (TNP-OVA). Stimulators were depleted of Mac-120+ macrophages using Mac-120 monoclonal antibody plus complement. TNP-Mac-120 macrophages stimulated primed T cells nearly as well as TNP-unfractionated macrophages (which were about 40% Mac-120+). In contrast, although greater than 70% DR+, Mac-120- macrophages plus either TNP-OVA or TNP-PBMC sonicate elicited minimal responses compared to unfractionated macrophages plus antigen. After 21-28 days of in vitro priming, macrophage-depleted T cells were not stimulated to proliferate by either IL2 alone or sonicates alone. IL2 plus TNP-PBMC sonicates, however, stimulated significant proliferation. Furthermore, this response was considerably greater than that to IL2 plus either TNP-T cell sonicates or TNP-mouse spleen sonicates. Thus, the Mac-120+ macrophage population may have an important antigen-presenting and/or accessory function in the stimulation of primed T cells by soluble or particulate antigen, although it is unnecessary for responses to intact TNP-Ia+ PBMC. In addition, the data suggest that Ia+ sonicates alone may suffice for induction of IL2 responsiveness, but not for endogenous IL2 production and subsequent proliferation by primed T cells.

Angioimmunoblastic lymphadenopathy with hypogammaglobulinemia. Possible role of monocyte suppression

A patient wit angioimmunoblastic lymphadenopathy had low serum immunoglobulin values and no antibodies to injected immunogens. This occurred despite the proliferation of polyclonal B cells. T cells were deficient in number and in lymphoproliferative responses, but their helper and suppressor functions were maintained. Ia-antigen bearing leukocytes from the patient stimulated poorly in mixed leukocyte culture. In vitro immunoglobulin synthesis by mononuclear leukocytes form the patient was severely impaired. These leukocytes actively suppressed immunoglobulin synthesis by normal cells from healthy subjects in co-culture. The responsible cell had characteristics of a monocyte. The suppression was selective for humoral immunity and was manifest despite normal numbers of monocytes. It appears that heterogeneous immunoregulatory abnormalities can underlie the syndrome of angioimmunoblastic lymphadenopathy. Furthermore, monocyte suppressor abnormalities may be implicated in clinical disease phenomena.

Antigen presentation to human T lymphocytes. I. Different requirements for stimulation by hapten-modified cells vs. cell sonicates

We have investigated the cellular and antigenic requirements for incubation of secondary proliferative responses by human T lymphocytes. Two distinct properties of antigen-presenting peripheral blood mononuclear cells were studied: (a) the ability for appropriate cell surface constituents to construct an immunogenic moiety, and (b) the ability to present similar antigenic determinants when they are not covalently bound. Only Ia+ hapten-modified cells were effective stimulators. In contrast, both Ia+ and Ia- cell sonicates could stimulate secondary proliferative responses, but only in the presence of an accessory cell. This accessory cell was present in Ia+ macrophage, but not in Ia+ non-T lymphocyte, preparations. In contrast, macrophages or soluble factors produced by macrophages were not required for primed T cells to undergo hapten-specific proliferation in response to hapten-modified Ia+ stimulator cells. Thus, although all Ia+ cells tested can stimulate primed cells to proliferate, not all Ia+ cells can function as accessory cells for responses to sonicates. This may reflect the unique ability of a subpopulation(s) of Ia+ cells to bind or process sonicates or soluble antigens for appropriate recognition by primed T cells.

Role of Ia-positive cells in induction of secondary human immune responses to haptens in vitro

We have described techniques for induction of primary and secondary human immune responses in vitro to lymphoid cells modified with trinitrophenyl, dinitrophenyl, and fluorescein isothiocyanate. Optimal secondary proliferative responses required the presentation of hapten on stimulator cells that shared HLA-D region determinants with the responder cell and/or the original stimulator cell. In contrast, hapten-specific cytotoxic responses assessed on modified allogeneic targets with no detected HLA homology with the responder were comparable in magnitude to those detected on modified autologous targets. Furthermore, secondary proliferative, but not cytotoxic, responses required presentation of Ia+ stimulator populations. Modified B cells, surface-immunoglobulin-negative, non T cells (null-cells), and Ia+ activated T cells all induced proliferative responses at least as effectively as equal numbers of hapten-conjugated macrophage/monocytes. Conversely, Ia(-) null cells and macrophages were entirely unable to stimulate. The data thus suggest that for proliferative responses, primed human T cells respond to modified lymphoid cells only when hapten is recognized in the context of Ia molecules.

Recognition of hapten-modified cells in vitro by human T-lymphocytes

Clearer definition of the recognitive structures of human T lymphocytes for antigens will be required to elucidate the molecular basis of diseases and immunological responses induced or regulated by normal or abnormal T-cell function. For this purpose we have investigated the cellular requirements for immune responses in vitro to trinitrophenyl-conjugated peripheral blood mononuclear cells. The responding cell was characterized as a T cell on the basis of rosetting with sheep erythrocytes. T-cell recognition of hapten in proliferative responses depended upon presentation of antigen in an appropriate stimulator-cell context. Neither autologous hapten-modified erythrocytes nor T cells restimulated responses of in vitro-primed lymphocytes. Moreover, hapten-conjugated non-T cells were more effective than modified unfractionated cells in restimulating proliferative responses. Both macrophages and non-T lymphocytes effectively restimulated hapten-conjugate responses.Cell-mixing experiments indicated that the failure of haptenated T cells to stimulate proliferative responses was not because of a lack of fresh macrophages; these experiments suggested instead that T cells do not express appropriate structures necessary to present haptenic determinants in an immunogenic form. Hapten-modified T cells, however, were capable of inducing primed lymphocytes to become efficient cytotoxic effector cells, indicating that T-cell recognitive units for stimulation of proliferative and cytotoxic responses are different. These data support the concept that for induction of proliferative responses, human T cells recognize conventional antigens in association with HLA-D-region-encoded Ia-like molecules.