Hyper-IgM immunodeficiency with disseminated cryptococcosis

Pediatric Cryptococcosis

BACKGROUND

Seroprevalence studies have shown that 70% of children are exposed to Cryptococcus , the most common cause of meningitis in people living with human immunodeficiency virus (HIV), but reported pediatric disease prevalence is much lower than in adults.

METHODS

PubMed and Ovid Global Health databases were searched with the terms "cryptococcosis," "cryptococcal meningitis," " Cryptococcus neoformans " or " Cryptococcus gattii ." All studies reporting pediatric specific data in the English language from 1980 up until December 2022 were included.

RESULTS

One hundred sixty-eight publications were reviewed totaling 1469 children, with the majority reported from Africa (54.2%). Sixty-five percent (961) were HIV positive, 10% (147) were non-HIV immunocompromised and 19% (281) were immunocompetent. Clinical signs and symptoms were only reported for 458 children, with fever (64%), headache (55%) and vomiting (39%) being the most common. Most children (80%) suffered from meningoencephalitis. Lung involvement was rarely described in HIV-positive children (1%), but significantly more common in the non-HIV immunocompromised (36%) and immunocompetent (40%) groups ( P < 0.0001). Only 22% received the recommended antifungal combination therapy, which was significantly higher in immunocompetent children than those with HIV (39% vs. 6.8%; P < 0.0001). Overall mortality was 23%. A significant higher mortality was observed in children with HIV compared with immunocompetent children (32% vs. 16%; P < 0.001), but not compared with children with non-HIV immunosuppression (25).

CONCLUSIONS

This is the largest review of pediatric cryptococcosis with new observations on differences in clinical presentation and outcome depending on the underlying condition. The lack of granular clinical data urges prospective clinical epidemiological studies for improved insight in the epidemiology, management and outcome of cryptococcosis in children.

Cryptococcal Meningoencephalitis in Phenotypically Normal Patients

Cryptococcosis is an invasive fungal infection found worldwide that causes significant morbidity and mortality among a broad range of hosts. There are approximately 223,000 new cases of cryptococcosis annually throughout the world, and at least 180,000 deaths are attributed to this infection each year. Most of these are due to complications of cryptococcal meningoencephalitis among HIV-infected patients in resource-limited environments. The majority of individuals diagnosed with cryptococcosis have underlying conditions associated with immune dysfunction such as HIV, solid organ transplant, hematologic malignancy, organ failure syndromes, and/or the use of immunosuppressive agents such as glucocorticosteroids and biologic agents. In most clinical series, there is a small proportion of patients with cryptococcosis who are phenotypically normal; that is, they have no clinically obvious predisposition to disease. Cryptococcal meningoencephalitis (CME) presentation and management differ substantially between these normal individuals and their immunocompromised counterparts. In this review, we will focus on CME in the phenotypically normal host and underscore differences in the clinical presentation, management, outcome, and potential risk factors for these patients compared to immunocompromised persons who develop this potential devastating invasive fungal infection.

How metals fuel fungal virulence, yet promote anti-fungal immunity

Invasive fungal infections represent a significant global health problem, and present several clinical challenges, including limited treatment options, increasing rates of antifungal drug resistance and compounding comorbidities in affected patients. Metals, such as copper, iron and zinc, are critical for various biological and cellular processes across phyla. In mammals, these metals are important determinants of immune responses, but pathogenic microbes, including fungi, also require access to these metals to fuel their own growth and drive expression of major virulence traits. Therefore, host immune cells have developed strategies to either restrict access to metals to induce starvation of invading pathogens or deploy toxic concentrations within phagosomes to cause metal poisoning. In this Review, we describe the mechanisms regulating fungal scavenging and detoxification of copper, iron and zinc and the importance of these mechanisms for virulence and infection. We also outline how these metals are involved in host immune responses and the consequences of metal deficiencies or overloads on how the host controls invasive fungal infections.

Importance of Clinical Isolates in Cryptococcus neoformans Research

The human pathogenic fungus Cryptococcus neoformans is a global health concern. Previous research in the field has focused on studies using reference strains to identify virulence factors, generate mutant libraries, define genomic structures, and perform functional studies. In this review, we discuss the benefits and drawbacks of using reference strains to study C. neoformans, describe how the study of clinical isolates has expanded our understanding of pathogenesis, and highlight how studies using clinical isolates can further develop our understanding of the host-pathogen interaction during C. neoformans infection.

Inborn Errors of Immunity Causing Pediatric Susceptibility to Fungal Diseases

Inborn errors of immunity are a heterogeneous group of genetically determined disorders that compromise the immune system, predisposing patients to infections, autoinflammatory/autoimmunity syndromes, atopy/allergies, lymphoproliferative disorders, and/or malignancies. An emerging manifestation is susceptibility to fungal disease, caused by yeasts or moulds, in a superficial or invasive fashion. In this review, we describe recent advances in the field of inborn errors of immunity associated with increased susceptibility to fungal disease.

Use of Clinical Isolates to Establish Criteria for a Mouse Model of Latent Cryptococcus neoformans Infection

The mechanisms of latency in the context of C. neoformans infection remain poorly understood. Two reasons for this gap in knowledge are: 1) the lack of standardized criteria for defining latent cryptococcosis in animal models and 2) limited genetic and immunological tools available for studying host parameters against C. neoformans in non-murine models of persistent infection. In this study, we defined criteria required for latency in C. neoformans infection models and used these criteria to develop a murine model of persistent C. neoformans infection using clinical isolates. We analyzed infections with two clinical C. neoformans strains, UgCl223 and UgCl552, isolated from advanced HIV patients with cryptococcal meningitis. Our data show that the majority of C57BL/6 mice infected with the clinical C. neoformans isolates had persistent, stable infections with low fungal burden, survived beyond 90 days-post infection, exhibited weight gain, had no clinical signs of disease, and had yeast cells contained within pulmonary granulomas with no generalized alveolar inflammation. Infected mice exhibited stable relative frequencies of pulmonary immune cells during the course of the infection. Upon CD4+ T-cell depletion, the CD4DTR mice had significantly increased lung and brain fungal burden that resulted in lethal infection, indicating that CD4+ T-cells are important for control of the pulmonary infection and to prevent dissemination. Cells expressing the Tbet transcription factor were the predominant activated CD4 T-cell subset in the lungs during the latent infection. These Tbet-expressing T-cells had decreased IFNγ production, which may have implications in the capacity of the cells to orchestrate the pulmonary immune response. Altogether, these results indicate that clinical C. neoformans isolates can establish a persistent controlled infection that meets most criteria for latency; highlighting the utility of this new mouse model system for studies of host immune responses that control C. neoformans infections.

Associations between Cryptococcus Genotypes, Phenotypes, and Clinical Parameters of Human Disease: A Review

The genus Cryptococcus contains two primary species complexes that are significant opportunistic human fungal pathogens: C. neoformans and C. gattii. In humans, cryptococcosis can manifest in many ways, but most often results in either pulmonary or central nervous system disease. Patients with cryptococcosis can display a variety of symptoms on a spectrum of severity because of the interaction between yeast and host. The bulk of our knowledge regarding Cryptococcus and the mechanisms of disease stem from in vitro experiments and in vivo animal models that make a fair attempt, but do not recapitulate the conditions inside the human host. To better understand the dynamics of initiation and progression in cryptococcal disease, it is important to study the genetic and phenotypic differences in the context of human infection to identify the human and fungal risk factors that contribute to pathogenesis and poor clinical outcomes. In this review, we summarize the current understanding of the different clinical presentations and health outcomes that are associated with pathogenicity and virulence of cryptococcal strains with respect to specific genotypes and phenotypes.

Diagnosis of Hyper IgM syndrome in a Previously Healthy Adolescent Boy Presented with Cutaneous and Cerebral Cryptococcosis

X-linked hyper IgM (X-HIGM) syndrome is a combined immunodeficiency disease caused by mutations in the CD40LG gene, leading to a defect in immunoglobulin (Ig) class switching recombination and effector T-cell responses. X-HIGM patients usually present in early life with pyogenic bacterial and opportunistic infections. Herein, we report a previously healthy 13-year-old Thai boy who first presented with cutaneous and meningoencephalitis cryptococcosis. Whole-exome sequencing revealed that he was hemizygous for a missense c.514T>C (p.Tyr172His) in CD40LG, confirming a diagnosis of X-HIGM. This report demonstrates that X-HIGM could have an age of onset in teens and systemic cryptococcosis could be its presenting symptoms.

Cryptococcal pneumonia in an adolescent with a gain-of-function variant in signal transduction and activator of transcription 1 (STAT1)

An adolescent male with a history of autoimmune enteropathy, autoimmune hypothyroidism, aphthous stomatitis and recurrent oral Candida infections only in the setting of curative antibiotic courses presented with cryptococcal pneumonia and perihilar adenitis, which was successfully treated with antifungal therapy. The patient had a complex history with several immunological anomalies. Whole exome sequencing revealed a known STAT1 pathogenic variant, associated with gain of function (GOF). This case expands our understanding of the broad clinical phenotype manifested by STAT1 GOF and emphasises the importance of consideration of this diagnosis in patients presenting with opportunistic infections and autoimmunity.

Catheter-related infection due to Papiliotrema laurentii in an oncologic patient: Case report and systematic review

Background

Papiliotrema laurentii is one of several non-neoformans cryptococci that have rarely been associated with human infection, since it was previously considered saprophyte and thought to be non-pathogenic to humans. Nevertheless, increasing number of reports of human infection have emerged in recent years, mostly in oncologic patients.

Aim

To report a case of a female patient with pyloric obstructive cancer with a catheter-related Papiliotrema laurentii blood stream infection and systematically review the available evidence on P. laurentii infection in humans.

Methods

Retrieval of studies was based on Medical Subject Headings and Health Sciences Descriptors, which were combined using Boolean operators. Searches were run on the electronic databases Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), Cochrane Library for Systematic Reviews and Opengray.eu. There was no language or date of publication restrictions. The reference lists of the studies retrieved were searched manually.

Results

The search strategy retrieved 1703 references. In the final analysis, 31 references were included, with the description of 35 cases. Every patient but one had a previous co-morbidity - 48.4 % of patients had a neoplasm. Amphotericin B was the most used treatment and only a single case of resistance to it was reported. Most patients were cured of the infection.

Conclusion

P. laurentii infection in humans is usually associated to neoplasia and multiple co-morbidities, and amphotericin B seems to be a reliable agent for treatment.

FATAL cryptococcal meningitis in a child with hyper-immunoglobulin M syndrome, with an emphasis on the agent

Following a fatal case of Cryptococcus neoformans meningitis in a child with X-linked hyper-immunoglobulin M syndrome (XHIGM), we evaluated the fungal isolate in an experimental infection in a mouse model with respect to microbiology, epidemiology, virulence and response to therapy. The minimum inhibitory concentrations for antifungals in the susceptibility test were 0.5mg/L for amphotericin B, 4.0mg/L for fluconazole and 0.12mg/L for voriconazole. Evaluation of pathogenicity by means of an experimental infection in BALB/c mice showed that fungus isolated from the blood and cerebrospinal fluid of the child was able to disseminate, reaching the spleen, lungs and brain, where it caused significant macroscopic alterations in the size and texture of each organ. Treatment of infected mice with amphotericin B reduced the fungal load in the spleen and lungs, but not in the brain.

The molecular immunology of human susceptibility to fungal diseases: lessons from single gene defects of immunity

INTRODUCTION

Fungal diseases are a threat to human health. Therapies targeting the fungus continue to lead to disappointing results. Strategies targeting the host response represent unexplored opportunities for innovative treatments. To do so rationally requires the identification and neat delineation of critical mechanistic pathways that underpin human antifungal immunity. The study of humans with single-gene defects of the immune system, i.e. inborn errors of immunity (IEIs), provides a foundation for these paradigms. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses was performed to review the history of genetic resistance/susceptibility to fungi and identify IEIs associated with fungal diseases. Immunologic mechanisms from relevant IEIs were integrated with current definitions and understandings of mycoses to establish a framework to map out critical immunobiological pathways of human antifungal immunity. Expert opinion: Specific immune responses non-redundantly govern susceptibility to their corresponding mycoses. Defining these molecular pathways will guide the development of host-directed immunotherapies that precisely target distinct fungal diseases. These findings will pave the way for novel strategies in the treatment of these devastating infections.

Cryptococcus deuterogattii VGIIa Infection Associated with Travel to the Pacific Northwest Outbreak Region in an Anti-Granulocyte-Macrophage Colony-Stimulating Factor Autoantibody-Positive Patient in the United States

Mortality rates associated with C. gattii infections are estimated to be between 13% and 33%, depending on an individual’s predisposition, and C. gattii has caused at least 39 deaths in the PNW region. There have been four other international travel cases reported in patients from Europe and Asia with travel history to the PNW, but this report describes the first North American traveler who acquired C. deuterogattii infection presenting within the United States and the first case of a C. deuterogattii outbreak infection associated with anti-GM-CSF autoantibodies. Early and accurate diagnoses are important for disease prevention and treatment and for control of infectious diseases. Continual reporting of C. deuterogattii infections is necessary to raise awareness of the ongoing outbreak in the PNW and to alert travelers and physicians to the areas of endemicity with potential risks.

The region encompassing the Pacific Northwest (PNW), Vancouver Island, Oregon, and Washington has been the location of an ongoing Cryptococcus gattii outbreak since the 1990s, and there is evidence that the outbreak is expanding along the West Coast into California. Here we report a clinical case of a 69-year-old, HIV-negative man from North Carolina who was diagnosed with a fungal brain mass by magnetic resonance imaging (MRI) and pathology. He had traveled to Seattle and Vancouver 3 years earlier and to Costa Rica 4 months prior to presentation. Phenotypic evidence showed that the fungal mass isolated from the patient’s brain represented C. gattii. In agreement with the phenotypic results, multilocus sequence typing (MLST) provided genotypic evidence that assigned the infecting organism within the C. gattii species complex and to the C. deuterogattii VGIIa clade. Whole-genome sequencing revealed >99.99% identity with the C. deuterogattii reference strain R265, indicating that the infecting strain is derived from the highly clonal outbreak strains in the PNW. We conclude that the patient acquired the C. gattii infection during his travel to the region 3 years prior and that the infection was dormant for an extended period of time before causing disease. The patient tested positive for anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies, supporting earlier reports that implicate these autoantibodies as a risk factor associated with C. gattii infection.

Scalp Lesions in a Pediatric Patient with Hyper IgM Syndrome: Clinical and Histologic Mimicry of Cryptococcus neoformans Infection

We report a case of cutaneous cryptococcosis due to Cryptococcus neoformans in a pediatric patient with hyper IgM syndrome with scalp lesions that resembled tinea capitis on gross examination and mimicked juvenile xanthogranuloma on histologic examination. This case highlights the importance of considering cutaneous cryptococcosis in patients with hyper IgM syndrome.

Adaptive Immunity to Cryptococcus neoformans Infections

The Cryptococcus neoformans/Cryptococcus gattii species complex is a group of fungal pathogens with different phenotypic and genotypic diversity that cause disease in immunocompromised patients as well as in healthy individuals. The immune response resulting from the interaction between Cryptococcus and the host immune system is a key determinant of the disease outcome. The species C. neoformans causes the majority of human infections, and therefore almost all immunological studies focused on C. neoformans infections. Thus, this review presents current understanding on the role of adaptive immunity during C. neoformans infections both in humans and in animal models of disease.

Cryptococcal Disease in HIV-Infected Children

Cryptococcus neoformans is an encapsulated fungal pathogen that is remarkable for its tendency to cause meningoencephalitis, especially in patients with AIDS. While disease is less common in children than adults, it remains an important cause of morbidity and mortality among HIV-infected children without access to anti-retroviral therapy. This review highlights recent insights into both the biology and treatment of cryptococcosis with a special emphasis on the pediatric literature.

Identification and characterization of Cryptococcus neoformans protein fractions that induce protective immune responses

Cryptococcus neoformans, the main causative agent of cryptococcosis, is a fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised patients. To date, there is no vaccine or immunotherapy approved to treat cryptococcosis. Cell- and antibody-mediated immune responses collaborate to mediate optimal protection against C. neoformans infections. Accordingly, we identified cryptococcal protein fractions capable of stimulating cell- and antibody-mediated immune responses and determined their efficacy to elicit protection against cryptococcosis. Proteins were extracted from C. neoformans and fractionated based on molecular mass. The fractions were then evaluated by immunoblot analysis for reactivity to serum extracted from protectively immunized mice and in cytokine recall assays for their efficacy to induce pro-inflammatory and Th1-type cytokine responses associated with protection. MS analysis revealed a number of proteins with roles in stress response, signal transduction, carbohydrate metabolism, amino acid synthesis, and protein synthesis. Immunization with select protein fractions containing immunodominant antigens induced significantly prolonged survival against experimental pulmonary cryptococcosis. Our studies support using the combination of immunological and proteomic approaches to identify proteins that elicit antigen-specific antibody and Th1-type cytokine responses. The immunodominant antigens that were discovered represent attractive candidates for the development of novel subunit vaccines for treatment and/or prevention of cryptococcosis.

Cryptococcus antigens and immune responses: implications for a vaccine

Cryptococcosis is a fungal disease primarily occurring in immunocompromised individuals, such as AIDS patients, and is associated with high morbidity and mortality. However, cryptococcosis can occur within immunocompetent populations as observed during an outbreak in Vancouver Island, British Columbia, Canada, the Pacific Northwest and other regions of the USA and in Mediterranean Europe. Mortality rates due to cryptococcosis have significantly declined in economically developed countries since the widespread implementation of highly active antiretroviral therapy. However, the incidence and mortality of this disease remains high in economically undeveloped areas in Africa and Asia where HIV infections are high and availability of HAART is limited. The continuing AIDS epidemic coupled with the increased usage of immunosuppressive drugs to prevent organ transplant rejection or to treat autoimmune diseases has resulted in an increase in individuals at risk for developing cryptococcosis. The purpose of this review is to discuss the need, challenges and potential for developing vaccines against cryptococcosis.

Primary immunodeficiencies underlying fungal infections

PURPOSE OF REVIEW

We review the primary immunodeficiencies (PIDs) underlying an increasing variety of superficial and invasive fungal infections. We also stress that the occurrence of such fungal infections should lead physicians to search for the corresponding single-gene inborn errors of immunity. Finally, we suggest that other fungal infections may also result from hitherto unknown inborn errors of immunity, at least in some patients with no known risk factors.

RECENT FINDINGS

An increasing number of PIDs are being shown to underlie fungal infectious diseases in children and young adults. Inborn errors of the phagocyte NADPH oxidase complex (chronic granulomatous disease), severe congenital neutropenia (SCN) and leukocyte adhesion deficiency type I confer a predisposition to invasive aspergillosis and candidiasis. More rarely, inborn errors of interferon-γ immunity underlie endemic mycoses. Inborn errors of interleukin-17 immunity have recently been shown to underlie chronic mucocutaneous candidiasis (CMC), while inborn errors of caspase recruitment domain-containing protein 9 (CARD9) immunity underlie deep dermatophytosis and invasive candidiasis.

SUMMARY

CMC, invasive candidiasis, invasive aspergillosis, deep dermatophytosis, pneumocystosis, and endemic mycoses can all be caused by PIDs. Each type of infection is highly suggestive of a specific type of PID. In the absence of overt risk factors, single-gene inborn errors of immunity should be sought in children and young adults with these and other fungal diseases.

Immunoglobulin class switch recombination deficiency type 1 or CD40 ligand deficiency: from bedside to bench and back again

The immunoglobulin class switch recombination deficiency or hyper-IgM syndrome is characterized by normal or elevated serum IgM and low serum levels of other immunoglobulins. Since the first reported patient with hyper-IgM, more than 200 patients with this phenotype resulted from CD40 ligand deficiency have been reported. However, in addition to this common finding, they presented with different manifestations like opportunistic infections, autoimmunity and malignancies each of them are worth a detailed look. In this review, we will focus on different underlying mechanisms of these presentations to review what we have learned from our patients. In the end, we will discuss different treatment options available for these patients using this knowledge.

Vaccine and immunotherapeutic approaches for the prevention of cryptococcosis: lessons learned from animal models

Cryptococcus neoformans and C. gattii, the predominant etiological agents of cryptococcosis, can cause life-threatening infections of the central nervous system in immunocompromised and immunocompetent individuals. Cryptococcal meningoencephalitis is the most common disseminated fungal infection in AIDS patients, and C. neoformans remains the third most common invasive fungal infection among organ transplant recipients. Current anti-fungal drug therapies are oftentimes rendered ineffective due to drug toxicity, the emergence of drug resistant organisms, and/or the inability of the host's immune defenses to assist in eradication of the yeast. Therefore, there remains an urgent need for the development of immune-based therapies and/or vaccines to combat cryptococcosis. Studies in animal models have demonstrated the efficacy of various vaccination strategies and immune therapies to induce protection against cryptococcosis. This review will summarize the lessons learned from animal models supporting the feasibility of developing immunotherapeutics and vaccines to prevent cryptococcosis.

Disseminated cryptococcal infection in patient with novel JAK3 mutation severe combined immunodeficiency, with resolution after stem cell transplantation

Disseminated cryptococcal infection is the second most common cause of death after tuberculosis in acquired immune deficiency syndrome patients. Surprisingly, it has been reported only in few patients with primary immunodeficiency diseases. Herein, we report the clinical presentation and outcome of a 23-month-old boy with novel JAK3 mutation severe combined immunodeficiency disease complicated by severe disseminated cryptococcal infection.

Fungal infections in primary immunodeficiencies

Patients with phagocytic, cellular, combined and other primary immunodeficiencies exhibit immune deficits that confer increased susceptibility to fungal infections. A number of yeasts and moulds, most commonly Candida and Aspergillus but also Cryptococcus, Histoplasma, Paecilomyces, Scedosporium, Trichosporon, Penicillium and other, rarely isolated, fungal organisms, have been variably implicated in causing disease in patients with chronic granulomatous disease, severe combined immunodeficiency, chronic mucocutaneous candidiasis, hyper-IgE syndrome, myeloperoxidase deficiency, leukocyte adhesion deficiency, defects in the interferon-gamma/interleukin-12 axis, DiGeorge syndrome, X-linked hyper-IgM syndrome, Wiskott-Aldrich syndrome and common variable immunodeficiency. Differences in the spectrum of fungal pathogens as well as in the incidence and clinical presentation of the infections may be observed among patients, depending upon different immune disorders. Fungal infections in these individuals may occasionally be the presenting clinical manifestation of a primary immunodeficiency and can cause significant morbidity and potentially fatal outcome if misdiagnosed or mistreated. A high degree of suspicion is needed and establishment of diagnosis should actively be pursued using appropriate imaging, mycological and histological studies. A number of antifungal agents introduced over the last fifteen years, such as the lipid formulations of amphotericin B, the second-generation triazoles, and the echinocandins, increase the options for medical management of these infections. Surgery may also be needed in some cases, while the role of adjunctive immunotherapy has not been systematically evaluated. The low incidence of primary immunodeficiencies in the general population complicates single-center prospective or retrospective clinical studies aiming to address diagnostic or therapeutic issues pertaining to fungal infections in these patients.

Antibody response to Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan in patients after solid-organ transplantation

Cryptococcosis is an important complication of solid-organ transplantation, but the risk factors for disease are poorly understood. The goal of this study was to investigate whether specific or nonspecific serum immunoglobulin levels determined in samples obtained before and after solid-organ transplantation differed in patients who did or did not develop cryptococcosis after transplantation. We analyzed pretransplantation sera from 25 subjects, 15 who subsequently developed cryptococcosis and 10 who did not, and posttransplantation sera from 24 subjects, 13 who developed cryptococcosis and 11 who did not. All subjects received a tacrolimus-based immunosuppressive regimen. Total immunoglobulin levels were measured by immunodiffusion, and Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM)-specific serum antibody levels were determined by enzyme-linked immunosorbent assays. The results showed that solid-organ transplantation had a significant effect on total immunoglobulin and GXM-reactive antibody levels. GXM-reactive antibody levels differed in subjects who did and did not develop cryptococcosis. In pretransplant serum samples, the levels of GXM-reactive immunoglobulin M (IgM) were significantly lower in subjects who developed cryptococcosis after transplantation than in those who did not. For posttransplant serum samples, the levels of GXM-reactive IgM and IgG were significantly higher among the subjects who developed cryptococcosis than among those who did not. These findings suggest that perturbations in the preexisting antibody or B-cell repertoire and/or related to treatment of rejection, transplantation, or immunosuppressive therapy could translate into an increased risk for transplant-associated cryptococcosis.

Cryptococcus neoformans-reactive and total immunoglobulin profiles of human immunodeficiency virus-infected and uninfected Ugandans

We determined total and Cryptococcus neoformans glucuronoxylomannan (GXM)-reactive antibody repertoires of human immunodeficiency virus (HIV)-infected and HIV-uninfected Ugandans in a retrospective, case-control study of participants in a randomized controlled trial of pneumococcal vaccination. The study included 192 adults: 48 who subsequently developed cryptococcal meningitis (CM); (HIV+ CM+); 2 individuals who matched them in CD4+ T-cell level, stage of HIV disease, and age but did not develop CM (HIV+ CM-); and 48 HIV-uninfected individuals. Total serum immunoglobulin concentrations and titers of immunoglobulin M (IgM), IgG, and IgA to GXM, pneumococcal polysaccharides, and antibodies expressing certain V(H)3 idiotypes were determined with banked sera obtained before the development of cryptococcosis for HIV+ CM+ subjects. The results showed that HIV-infected subjects had significantly lower levels of IgM to GXM but higher levels of total immunoglobulin and IgG and IgA to GXM than those of HIV-uninfected subjects. HIV-infected subjects with a history of pneumonia had higher levels, and those with a history of herpes zoster had lower levels of GXM-binding antibodies than subjects with no history of either disease. Minimal to no cross-reactivity was demonstrated between antibodies to GXM and polysaccharides in a pneumococcal vaccine. No significant differences between the antibody repertoires of HIV+ CM+ and HIV+ CM- subjects were identified, but among subjects without a history of pneumonia, there was a trend towards lower V(H)3-positive antibody levels among HIV+ CM+ than among HIV+ CM- subjects. Our findings demonstrate an association between previous infectious diseases and differences in the total and GXM-reactive antibody repertoires of HIV-infected subjects and suggest the question of whether certain microbes modulate subsequent antibody responses to GXM deserves further study.

Cryptococcal meningitis in a patient with X-linked hyper-IgM1 syndrome

A case is reported of cryptococcal meningitis in a 27-y-old male suffering from X-linked hyper-IgM1 syndrome. This congenital disorder is characterized by multiple infections of the respiratory and gastrointestinal tracts, but also opportunistic infections commonly seen in patients with cell-mediated immunity. His clinical recovery was good but the need for life-long secondary chemoprophylaxis to prevent relapses is unknown.

A ten-year-old boy with a pulmonary nodule secondary to Cryptococcus neoformans: case report and review of the literature

Pulmonary cryptococcosis is an uncommonly recognized disease of childhood. Among immunocompetent and non-HIV-infected individuals, pulmonary cryptococcosis may be asymptomatic or present with chronic, nondescript symptomatology. In this report we describe a 10-year-old with malignant fibrous histiocytoma of bone and a pulmonary nodule secondary to Cryptococcus neoformans. We use this case as a background to review the pediatric literature regarding pulmonary cryptococcosis and to discuss the utility of immunohistochemistry for diagnosis of this clinical entity.

An 8-y-old boy with acute stroke and radiological signs of cerebral vasculitis after recent Mycoplasma pneumoniae infection

A young boy was admitted to hospital for acute stroke. Cerebral angiography showed a pattern suggestive of vasculitis and a recent Mycoplasma pneumoniae infection was detected. The absence of microorganisms in cerebrospinal fluid, the pattern of vasculitis and previous reports supporting a post-infectious immunological mechanism for certain complications of M. pneumoniae infection suggest this mechanism as the cause of the stroke.

Hyper-IgM syndrome with systemic tuberculosis

A 33-y-old man with Hyper-IgM syndrome developed a severe tuberculous disease complicated by pleuritis and spondylitis. An abnormally decreased CD4/CD8 ratio, decreased CD4 + T-cell count and depressed natural killer cell activity implicated a coexistent cell-mediated immunodeficiency. To our knowledge, this is the first detailed report of tuberculosis associated with Hyper-IgM syndrome.

Cryptococcosis

Cryptococcus neoformans has risen to a worldwide highly recognizable major opportunistic pathogen with deadly consequences. It has become a model fungus to study a variety of paradigms in the host-fungus relationships. Genomic studies are advancing knowledge on its evolution and dissecting its virulence composite. Studies designed to understand host immunology to this fungus are leading to development of active and passive prevention and therapeutic strategies. This article collates and analyzes both new and old knowledge about the pathogen to help frame the meaning of human cryptococcosis as it starts to evolve in the new millennium.

Mutations of the CD40 Ligand Gene and Its Effect on CD40 Ligand Expression in Patients With X-Linked Hyper IgM Syndrome

X-linked hyper IgM syndrome (XHIM) is a primary immunodeficiency disorder caused by mutations of the gene encoding CD40 ligand (CD40L). We correlated mutations of the CD40L gene, CD40L expression, and the clinical manifestations observed in XHIM patients from 30 families. The 28 unique mutations identified included 9 missense, 5 nonsense, 9 splice site mutations, and 5 deletions/insertions. In 4 of 9 splice site mutations, normally spliced and mutated mRNA transcripts were simultaneously expressed. RNase protection assay demonstrated that 5 of 17 mutations tested resulted in decreased levels of transcript. The effect of the mutations on CD40L expression by activated peripheral blood mononuclear cells (PBMC) and T-cell lines or clones was assessed using one polyclonal and four monoclonal antibodies and a CD40-Ig fusion protein. In most patients, the binding of at least one antibody but not of CD40-Ig was observed, suggesting nonfunctional CD40L. However, activated PBMC from three patients and activated T-cell lines from two additional patients, each with different genotype, bound CD40-Ig at low intensity, suggesting functional CD40L. Thus, failure of activated PBMC to bind CD40-Ig is not an absolute diagnostic hallmark of XHIM and molecular analysis of the CD40L gene may be required for the correct diagnosis. Patients with genotypes resulting in diminished expression of wild-type CD40L or mutant CD40L that can still bind CD40-Ig appear to have milder clinical consequences.

Mutations of the CD40 Ligand Gene and Its Effect on CD40 Ligand Expression in Patients With X-Linked Hyper IgM Syndrome

X-linked hyper IgM syndrome (XHIM) is a primary immunodeficiency disorder caused by mutations of the gene encoding CD40 ligand (CD40L). We correlated mutations of the CD40L gene, CD40L expression, and the clinical manifestations observed in XHIM patients from 30 families. The 28 unique mutations identified included 9 missense, 5 nonsense, 9 splice site mutations, and 5 deletions/insertions. In 4 of 9 splice site mutations, normally spliced and mutated mRNA transcripts were simultaneously expressed. RNase protection assay demonstrated that 5 of 17 mutations tested resulted in decreased levels of transcript. The effect of the mutations on CD40L expression by activated peripheral blood mononuclear cells (PBMC) and T-cell lines or clones was assessed using one polyclonal and four monoclonal antibodies and a CD40-Ig fusion protein. In most patients, the binding of at least one antibody but not of CD40-Ig was observed, suggesting nonfunctional CD40L. However, activated PBMC from three patients and activated T-cell lines from two additional patients, each with different genotype, bound CD40-Ig at low intensity, suggesting functional CD40L. Thus, failure of activated PBMC to bind CD40-Ig is not an absolute diagnostic hallmark of XHIM and molecular analysis of the CD40L gene may be required for the correct diagnosis. Patients with genotypes resulting in diminished expression of wild-type CD40L or mutant CD40L that can still bind CD40-Ig appear to have milder clinical consequences.

Cryptococcosis: an unusual opportunistic infection complicating B cell lymphoproliferative disorders

We report two cases of cryptococcosis in patients with Waldenstrom's macroglobulinaemia and chronic lymphocytic leukaemia that responded to prolonged therapy with systemic amphotericin and flucytosine. Cryptococcosis, although more common in those with impaired cell mediated immunity, should also be considered as a complication in patients with impaired antibody responses.

The induction of a protective response in Leishmania major-infected BALB/c mice with anti-CD40 mAb

A protective immune response to the intracellular parasite Leishmania major requires the development of a Th1 CD4+ T cell phenotype. We demonstrate herein that BALB/c mice, which normally develop a susceptible Th2 response to L. major infection, are protected when co-injected with an agonistic anti-murine CD40 mAb. Anti-CD40 mAb-mediated protection in this system was found to be T cell dependent, since it was not observed in C57BL/6 x 129 mice that were rendered T cell deficient (TCR beta-/- x TCR delta-/-) and L. major susceptible. Anti-CD40 mAb stimulation of L. major-infected BALB/c mice was accompanied by increased IL-12 and IFN-gamma production in draining lymph nodes, analyzed either by direct expression, or in an antigen-specific in vitro recall assay. The protective role of these cytokines was indicated by the finding that anti-CD40 mAb-mediated protection of L. major-infected BALB/c mice could be reversed by co-treating the animals with neutralizing anti-IL-12 and/or anti-IFN-gamma mAb. Collectively, these data suggest that BALB/c mice develop a protective Th1 CD4+ T cell response to L. major infection when co-injected with anti-CD40 mAb. While the CD40-CD40L interaction has been previously shown to be vital in the control of murine Leishmaniasis, the current study establishes in vivo that anti-CD40 mAb treatment alone is sufficient to protect BALB/c mice from L. major infection and raises the possibility of utilizing this approach for vaccination strategies.

Mucocutaneous manifestations of the hyper-IgM immunodeficiency syndrome

BACKGROUND

The recurrent pyogenic infections of patients with hyper-IgM syndrome are controlled by intravenous gamma globulin administration, but patients may suffer from early-onset oral ulcerations and warts.

OBJECTIVE

We have characterized the mucocutaneous manifestations associated with this condition to allow physicians to more readily identify it.

METHODS

Three male patients with the mucocutaneous manifestations of the hyper-IgM syndrome are described. In one, histopathologic examination of the oral mucosal lesion was performed.

RESULTS

Recurrent large, painful oral ulcerations can occur that are not necessarily associated with neutropenia nor do they respond to granulocyte colony-stimulating factor administration. Histopathologic examination of an ulcer showed a heavy infiltrate of mixed inflammatory cells. Warts tend to be widespread and resistant to traditional therapy.

CONCLUSION

Physicians should consider this uncommon condition when examining a male patient with severe oral ulcers or recalcitrant widespread warts.

Clinical spectrum of X-linked hyper-IgM syndrome

We report the clinical and immunologic features and outcome in 56 patients with X-linked hyper-IgM syndrome, a disorder caused by mutations in the CD40 ligand gene. Upper and lower respiratory tract infections (the latter frequently caused by Pneumocystis carinii), chronic diarrhea, and liver involvement (both often associated with Cryptosporidium infection) were common. Many patients had chronic neutropenia associated with oral and rectal ulcers. The marked prevalence of infections caused by intracellular pathogens suggests some degree of impairment of cell-mediated immunity. Although lymphocyte counts and in vitro proliferation to mitogens were normal, a defective in vitro proliferative response to antigens was observed in some patients, and additional defects of cell-mediated immunity may be presumed on the basis of current knowledge of CD40-ligand function. All patients received regular infusions of immunoglobulins. Four patients underwent liver transplantation because of sclerosing cholangitis, which relapsed in there. Three patients underwent bone marrow transplantation. Thirteen patients (23%) died of infection and/or liver disease. X-linked hyper-IgM syndrome, once considered a clinical variant of hypogammaglobulinemia, is a severe immunodeficiency with significant cellular involvement and a high mortality rate.

A role for B cells in resistance to Cryptococcus neoformans in mice

The role of B cells in immunity to Cryptococcus neoformans was investigated. Genetically targeted, B-cell-deficient mice (mu Mt) examined at various times after intravenous infection with C. neoformans 184 had lung and brain yeast burdens that were equivalent to tissue burdens in control B-cell-sufficient mice. Both B-cell-deficient and B-cell-sufficient control mice were effectively vaccinated by a sublethal intratracheal instillation of strain 184 yeast against a systemic infection with the C. neoformans strain carrying ura5; vaccinated control and vaccinated B-cell-deficient mice had equivalent brain and lung burdens of the ura5 strain 10 days after intravenous rechallenge. Additionally, B-cell-deficient and B-cell-sufficient vaccinated mice survived an intravenous rechallenge with a dose of yeast cells which is normally lethal for unimmunized mice. In further studies of the role of B cells in murine cryptococcosis, SCID mice were reconstituted with lymphocytes from B-cell-deficient and B-cell-sufficient mice. SCID mice reconstituted with lymphocytes from vaccinated B-cell-deficient animals failed to express effective adoptive immunity to C. neoformans brain infection. In contrast, SCID mice reconstituted with lymphocytes from vaccinated B-cell-sufficient mice had 10-fold fewer yeast cells in their brains than did uninfused SCID controls. However, SCID mice given lymphocytes from B-cell-deficient immune donors had fewer yeast cells in their lungs than did uninfused controls. Fewer CD4+ lymphocytes were recovered at 7 and 11 days after infection from the peripheral blood and spleens of SCID mice reconstituted with lymphocyte suspensions from B-cell-deficient animals than from the peripheral blood and spleens of SCID mice reconstituted with suspensions from B-cell-sufficient control donors. These data suggest that B cells can play an important role in host defense against Cryptococcus in the brain under conditions in which T-cell-mediated immunity is impaired.

Genomic structure and PCR-SSCP analysis of the human CD40 ligand gene: its application to prenatal screening for X-linked hyper-IgM syndrome

To develop a general method for analysis of the mutation and prenatal diagnosis of X-linked hyper-IgM syndrome (XHM), the human CD40 ligand (hCD40L) gene was cloned and sequenced with special reference to the 5' and 3' flanking regions and exon/intron boundaries. The hCD40L gene consists of five exons and four introns, as already reported by others. Two major transcription initiation sites were identified at 67 bp and 64 bp upstream from the ATG initiation codon. The hCD40L mRNA transcripts terminated at 321 bp, 327 bp and 987 bp downstream from the TGA stop codon. Based on the intronic sequences, oligonucleotide primers were designed for amplifying the coding region of each exon separately. Polymerase chain reaction--single-strand conformational polymorphism (PCR-SSCP) analysis was successfully applied to screening for the defective hCD40L gene in a family with XHM. The nonsense mutation, Trp140 (TGG)-->stop (TAG) in exon 5, was found in the mother and an affected child. We also performed prenatal diagnosis by PCR-SSCP during the first trimester of pregnancy in this family.

A single strand conformation polymorphism study of CD40 ligand. Efficient mutation analysis and carrier detection for X-linked hyper IgM syndrome

Mutations in the gene for CD40 ligand are responsible for the X-linked form of hyper IgM syndrome. However, no clinical or laboratory findings that reliably distinguish X-linked disease from other forms of hyper IgM syndrome have been reported, nor are there tests available that can be used to confidently provide carrier detection. To identify efficiently mutations in the gene for CD40 ligand, eight pairs of PCR primers that could be used to screen genomic DNA by single strand conformation polymorphism (SSCP) were designed. 11 different mutations were found in DNA from all 13 patients whose activated T cells failed to bind a recombinant CD40 construct. The exact nature of four of these mutations, a deletion and three splice defects, could not be determined by cDNA sequencing. In addition, SSCP analysis permitted rapid carrier detection in two families in whom the source of the mutation was most likely a male with gonadal chimerism who passed the disorder on to some but not all of his daughters. These studies document the utility of SSCP analysis for both mutation detection and carrier detection in X-linked hyper IgM syndrome.