Safety and efficacy of treatment using interleukin-2 in a patient with idiopathic CD4(+) lymphopenia and Mycobacterium avium-intracellulare

Drugs for treating infections caused by non-tubercular mycobacteria: a narrative review from the study group on mycobacteria of the Italian Society of Infectious Diseases and Tropical Medicine

BACKGROUND

Non-tuberculous mycobacteria (NTM) are generally free-living organism, widely distributed in the environment, with sporadic potential to infect. In recent years, there has been a significant increase in the global incidence of NTM-related disease, spanning across all continents and an increased mortality after the diagnosis has been reported. The decisions on whether to treat or not and which drugs to use are complex and require a multidisciplinary approach as well as patients' involvement in the decision process.

METHODS AND RESULTS

This review aims at describing the drugs used for treating NTM-associated diseases emphasizing the efficacy, tolerability, optimization strategies as well as possible drugs that might be used in case of intolerance or resistance. We also reviewed data on newer compounds highlighting the lack of randomised clinical trials for many drugs but also encouraging preliminary data for others. We also focused on non-pharmacological interventions that need to be adopted during care of individuals with NTM-associated diseases CONCLUSIONS: Despite insufficient efficacy and poor tolerability this review emphasizes the improvement in patients' care and the needs for future studies in the field of anti-NTM treatments.

Long-term outcome of progressive multifocal leukoencephalopathy with recombinant interleukin-2 treatment and an associated increase in the number of HPyV-2-specific T-cells: a case report

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by reactivation of the human polyomavirus 2 (HPyV-2). PML is associated with a high morbidity and mortality rate and there is currently no standard curative therapy. We report short-term immunologic response and long-term clinical outcomes in a patient diagnosed with follicular lymphoma (FL) who developed PML. Diagnosis of PML was established conclusively based on findings from a brain biopsy. The patient was treated with recombinant interleukin 2 (IL-2) and showed rapid clinical improvement. HPyV-2-specific T-cells were tracked longitudinally and correlation with clinical status, viral load, and radiographic imaging was documented. After the progression of the patient's FL, which required an allogeneic bone marrow transplant, the patient prophylactically received human leukocyte antigen-matched donor-derived HPyV-2 T-cells to prevent the recurrence of the PML as part of a clinical trial. Twelve years after the initial diagnosis of PML, he did not develop a relapse of his PML, supporting data that therapies that increase HPyV-2-specific T-cells, including IL-2, may be effective in the management of PML.

Understanding the Host in the Management of Pneumonia. An Official American Thoracic Society Workshop Report

Pneumonia causes a significant burden of disease worldwide. Although all populations are at risk of pneumonia, those at extremes of age and those with immunosuppressive disorders, underlying respiratory disease, and critical illness are particularly vulnerable. Although clinical practice guidelines addressing the management and treatment of pneumonia exist, few of the supporting studies focus on the crucial contributions of the host in pneumonia pathogenesis and recovery. Such essential considerations include the host risk factors that lead to susceptibility to lung infections; biomarkers reflecting the host response and the means to pursue host-directed pneumonia therapy; systemic effects of pneumonia on the host; and long-term health outcomes after pneumonia. To address these gaps, the Pneumonia Working Group of the Assembly on Pulmonary Infection and Tuberculosis led a workshop held at the American Thoracic Society meeting in May 2018 with overarching objectives to foster attention, stimulate research, and promote funding for short-term and long-term investigations into the host contributions to pneumonia. The workshop involved participants from various disciplines with expertise in lung infection, pneumonia, sepsis, immunocompromised patients, translational biology, data science, genomics, systems biology, and clinical trials. This workshop report summarizes the presentations and discussions and important recommendations for future clinical pneumonia studies. These recommendations include establishing consensus disease and outcome definitions, improved phenotyping, development of clinical study networks, standardized data and biospecimen collection and protocols, and development of innovative trial designs.

Host-directed therapy to combat mycobacterial infections

Upon infection, mycobacteria, such as Mycobacterium tuberculosis (Mtb) and nontuberculous mycobacteria (NTM), are recognized by host innate immune cells, triggering a series of intracellular processes that promote mycobacterial killing. Mycobacteria, however, have developed multiple counter‐strategies to persist and survive inside host cells. By manipulating host effector mechanisms, including phagosome maturation, vacuolar escape, autophagy, antigen presentation, and metabolic pathways, pathogenic mycobacteria are able to establish long‐lasting infection. Counteracting these mycobacteria‐induced host modifying mechanisms can be accomplished by host‐directed therapeutic (HDT) strategies. HDTs offer several major advantages compared to conventional antibiotics: (a) HDTs can be effective against both drug‐resistant and drug‐susceptible bacteria, as well as potentially dormant mycobacteria; (b) HDTs are less likely to induce bacterial drug resistance; and (c) HDTs could synergize with, or shorten antibiotic treatment by targeting different pathways. In this review, we will explore host‐pathogen interactions that have been identified for Mtb for which potential HDTs impacting both innate and adaptive immunity are available, and outline those worthy of future research. We will also discuss possibilities to target NTM infection by HDT, although current knowledge regarding host‐pathogen interactions for NTM is limited compared to Mtb. Finally, we speculate that combinatorial HDT strategies can potentially synergize to achieve optimal mycobacterial host immune control.

Expanding mechanistic insights into the pathogenesis of idiopathic CD4+ T cell lymphocytopenia

Idiopathic CD4+ T cell lymphocytopenia (ICL) is a heterogeneous syndrome presenting with persistent CD4+ T cell lymphopenia of unknown origin, and opportunistic infections in some patients. The underlying pathogenesis and appropriate management remain understudied. In this issue of the JCI, Perez-Diez and Wong et al. assessed the prevalence of autoantibodies from the sera of 51 adult ICL patients (out of a cohort of 72). Some patients showed high levels of IgG and IgM autoantibodies against numerous autoantigens, and some autoantibodies were specific for lymphocytes. The researchers implicate these autoantibodies as a possible pathogenic mechanism responsible for the reduction in circulating CD4+ T cells. This study goes beyond defining a mechanism in a complex, poorly defined disease; it also brings a renewed focus on ICL that will likely result in improved diagnostic evaluation and treatment.

Criptococosis y linfocitopenia T CD4 idiopática: Reporte de un caso

La linfocitopenia T CD4 idiopática (LCI) es un síndrome clínico inusual que se caracteriza por un déficit de células T CD4+ circulantes en ausencia de infección por VIH u otra condición de inmunosupresión. Los pacientes con dicha enfermedad pueden presentarse asintomáticos o con infecciones oportunistas, las más frecuentes son por criptococo, micobacterias o virales como herpes zoster. Presentamos el caso de un hombre de 32 años, sin antecedentes, en quien se descartó infección por retrovirus, con recuento de linfocitos T CD4+ menor a 300 células/m3; se diagnosticó LCI posterior al diagnóstico de criptococomas cerebrales mediante hallazgos imagenológicos los cuales fueron congruentes con estudios microbiológicos.

Idiopathic CD4 Lymphocytopenia: Current Insights

Idiopathic CD4 lymphocytopenia is a condition characterized by low CD4 counts. It is rare and most of the information about this illness comes from case reports. Presentation is usually in the 4th decade of life with opportunistic infections, autoimmune disease or neoplasia. The pathophysiology of this condition is not well understood. Management revolves around treatment of the presenting condition and close follow-up of these patients. This review presents a narrative summary of the current literature on idiopathic CD4 lymphocytopenia.

Personalizing the Management of Pneumonia

Pneumonia is a highly prevalent disease with considerable morbidity and mortality. However, diagnosis and therapy still rely on antiquated methods, leading to the vast overuse of antimicrobials, which carries risks for both society and the individual. Furthermore, outcomes in severe pneumonia remain poor. Genomic techniques have the potential to transform the management of pneumonia through deep characterization of pathogens as well as the host response to infection. This characterization will enable the delivery of selective antimicrobials and immunomodulatory therapy that will help to offset the disorder associated with overexuberant immune responses.

Idiopathic CD4 lymphocytopenia: Pathogenesis, etiologies, clinical presentations and treatment strategies

BACKGROUND

Idiopathic CD4 lymphocytopenia (ICL) is a rare condition characterized by an unexplained deficit of circulating CD4 T cells leading to increased risk of serious opportunistic infections. The pathogenesis, etiology, clinical presentation, and best treatment options remain unclear.

OBJECTIVE

To describe the clinical presentation, treatment strategies, and outcome of patients with ICL seen in a single referral center.

METHODS

In a retrospective study, from January 1993 to January 2014, the demographic characteristics, clinical presentation, and treatments of patients diagnosed with ICL were reviewed.

RESULTS

Twenty-four patients (14 female [58%] and 10 male [42%]) were evaluated. The mean age was 45 ± 17.6 years (range 7-76 years). Mean CD4 and CD8 T-cell counts at the time of diagnosis were 119 ± 84/mm³ (range 4-294/mm³) and 219 ± 258/mm³ (range 7-630/mm³), respectively. Seventeen patients (71%) had opportunistic infections, 4 (17%) had malignancies, and 3 (13%) had unexplained demyelinating disease and neurologic problems. Most patients had normal levels of immunoglobulins. Thirteen patients had abnormally low to absent response to phytohemagglutinin, concanavalin A, and antigens (candida and tetanus). Three patients had resolution of warts and 1 had mycobacterial lung infection on interleukin-2 with increases in CD4 count. The 11 patients on trimethoprim and sulfamethoxazole had no further hospital admissions for infections.

CONCLUSION

The pathogenesis of ICL remains unclear. Although only some patients are healthy, most patients present with opportunistic infections. There is no known standard treatment aside from prophylactic antibiotics.

Mycobacterium avium Complex Disease

Despite the ubiqitous nature of Mycobacterium avium complex (MAC) organisms in the environment, relatively few of those who are infected develop disease. Thus, some degree of susceptibility due to either underlying lung disease or immunosuppression is required. The frequency of pulmonary MAC disease is increasing in many areas, and the exact reasons are unknown. Isolation of MAC from a respiratory specimen does not necessarily mean that treatment is required, as the decision to treatment requires the synthesis of clinical, radiographic, and microbiologic information as well as a weighing of the risks and benefits for the individual patient. Successful treatment requires a multipronged approach that includes antibiotics, aggressive pulmonary hygiene, and sometimes resection of the diseased lung. A combination of azithromycin, rifampin, and ethambutol administered three times weekly is recommend for nodular bronchiectatic disease, whereas the same regimen may be used for cavitary disease but administered daily and often with inclusion of a parenteral aminoglycoside. Disseminated MAC (DMAC) is almost exclusively seen in patients with late-stage AIDS and can be treated with a macrolide in combination with ethambutol, with or without rifabutin: the most important intervention in this setting is to gain HIV control with the use of potent antiretroviral therapy. Treatment outcomes for many patients with MAC disease remain suboptimal, so new drugs and treatment regimens are greatly needed. Given the high rate of reinfection after cure, one of the greatest needs is a better understanding of where infection occurs and how this can be prevented.

Personalized Medicine for Chronic Respiratory Infectious Diseases: Tuberculosis, Nontuberculous Mycobacterial Pulmonary Diseases, and Chronic Pulmonary Aspergillosis

Chronic respiratory infectious diseases are causing high rates of morbidity and mortality worldwide. Tuberculosis, a major cause of chronic pulmonary infection, is currently responsible for approximately 1.5 million deaths per year. Although important advances in the fight against tuberculosis have been made, the progress towards eradication of this disease is being challenged by the dramatic increase in multidrug-resistant bacilli. Nontuberculous mycobacteria causing pulmonary disease and chronic pulmonary aspergillosis are emerging infectious diseases. In contrast to other infectious diseases, chronic respiratory infections share the trait of having highly variable treatment outcomes despite longstanding antimicrobial therapy. Recent scientific progress indicates that medicine is presently at a transition stage from programmatic to personalized management. We explain current state-of-the-art management concepts of chronic pulmonary infectious diseases as well as the underlying methods for therapeutic decisions and their implications for personalized medicine. Furthermore, we describe promising biomarkers and techniques with the potential to serve future individual treatment concepts in this field of difficult-to-treat patients. These include candidate markers to improve individual risk assessment for disease development, the design of tailor-made drug therapy regimens, and individualized biomarker-guided therapy duration to achieve relapse-free cure. In addition, the use of therapeutic drug monitoring to reach optimal drug dosing with the smallest rate of adverse events as well as candidate agents for future host-directed therapies are described. Taken together, personalized medicine will provide opportunities to substantially improve the management and treatment outcome of difficult-to-treat patients with chronic respiratory infections.

A rare case of idiopathic cluster of differentiation 4(+) T-cell lymphocytopenia presenting with disseminated tubercular infection

Idiopathic cluster of differentiation 4⁺ (CD4⁺) T-cell lymphocytopenia is a rare heterogeneous clinical syndrome characterized by low absolute CD4 counts on two different occasions without any evidence of other known cause of immunodeficiency including human immunodeficiency virus (HIV), infections or drugs associated with fall in CD4⁺ count. Also referred to as severe unexplained HIV seronegative immune suppression by the World Health Organization, it was first described by Centers for Disease Control in 1992 in patients with opportunistic infections who were negative for HIV but had low CD4 counts. Patients typically present with opportunistic infections, malignancies, or autoimmune disorders. There have been case reports on opportunistic infections such as cryptococcal meningitis or non-Mycobacterium tuberculosis infections in these patients. However, no case of disseminated M. tuberculosis has been reported as such in Indian literature. We present a case of disseminated tuberculosis with low CD4 counts without any evidence of HIV infection.

Idiopathic lymphocytopenia

PURPOSE OF REVIEW

Idiopathic CD4⁺ lymphocytopenia (ICL) is defined by the reduction of the main lymphocyte subtype in peripheral blood and CD4⁺ T cells below 300/μl in the absence of any secondary known causes of lymphopenia, including viral causes. The present review aims to state the latest available data on clinical, pathological and therapeutic aspects related to ICL, published from 1990 to 2014. The last observed clinical presentation and complications of ICL patients are described. The latest findings and possible mechanisms involved in the development of ICL features are included in the present review; however, pathogenesis of ICL has remained mainly obscured. Finally, recent therapeutic efforts considered in ICL patients are discussed.

RECENT FINDINGS

In spite of the serious complications ICL has on the patients' quality of life, data on clinical, etiopathological and therapeutic behavior for ICL are very limited. On one side, an abnormal blood cell count may be the sole presentation; however, occurrence of disseminated malignant tumors is not uncommon in patients. Recent findings highlight the role of cytokines, especially interleukin-2, on features such as phenotype severity and responsiveness of the condition to therapy. In addition, some studies have suggested that a defect in hematopoietic stem cells may be involved in disease progression, an idea that is supported by the success of bone marrow transplantation in acquiring persistent remissions in ICL patients.

SUMMARY

ICL is a hematologic condition of increasing importance due to its diverse clinical and pathological spectrum. Molecular studies have shown the presence of mutations involved in lymphocyte development as potential factors that may contribute to ICL occurrence. ICL patients could present either with common infections or really serious malignant conditions. The role of cytokines, especially interleukin-2, has emerged as one of the main possible mechanisms involved in clinical and pathological behavior of ICL. Today, the main therapeutic approaches are controlling life-threatening infections and underlying disorders along with efforts to cure ICL through rising CD4⁺ cell counts using cytokine interventions and transplantation.

Cytokine immunomodulation for the treatment of infectious diseases: lessons from primary immunodeficiencies

Traditionally, management of infectious diseases focuses on identification of the causative microbe and the use of pathogen-targeted therapy. With increasing antimicrobial resistance, novel approaches are required. One strategy is to modulate those natural host immune responses that critically mediate resistance to specific microbes. Clinically, this host-directed tactic could be used either alone or in combination with antimicrobial therapy. While conceptually attractive, there is potential concern that the pathways governing host resistance to pathogens in animal models may not extrapolate linearly to humans. Targeting these immune processes clinically may precipitate damaging, epiphenomenal responses. The field of Primary Immunodeficiencies focuses on the characterization of humans with inborn errors of immunity. These rare conditions permit the identification of those molecular and cellular processes that are central to human susceptibility to microbes. In efforts to compensate for defective host responses, this field has also provided a wealth of clinical experience in the effective use of cytokines to treat various active infections, while demonstrating their safety. In this review, we provide a historical perspective of the treatment of infectious diseases, evolving from a focus on the microbe, to an understanding of human immunity; we then outline the growing contribution of Primary Immunodeficiencies to the rational use of adjunctive cytokine immunotherapy in the management of infections.

Idiopathic CD4 lymphocytopenia: clinical and immunologic characteristics and follow-up of 40 patients

Idiopathic CD4 T lymphocytopenia (ICL) is a rare and severe condition with limited available data. We conducted a French multicenter study to analyze the clinical and immunologic characteristics of a cohort of patients with ICL according to the Centers for Disease Control criteria.We recruited 40 patients (24 female) of mean age 44.2 ± 12.2 (19-70) years. Patients underwent T-lymphocyte phenotyping and lymphoproliferation assay at diagnosis, and experiments related to thymic function and interferon (IFN)-γ release by natural killer (NK) cell were performed. Mean follow-up was 6.9 ± 6.7 (0.14-24.3) years. Infectious, autoimmune, and neoplastic events were recorded, as were outcomes of interleukin 2 therapy.In all, 25 patients had opportunistic infections (12 with human papillomavirus infection), 14 had autoimmune symptoms, 5 had malignancies, and 8 had mild or no symptoms. At the time of diagnosis, the mean cell counts were as follows: mean CD4 cell count: 127/mm (range, 4-294); mean CD8: 236/mm (range, 1-1293); mean CD19: 113/mm (range, 3-547); and mean NK cell count: 122/mm (range, 5-416). Most patients had deficiency in CD8, CD19, and/or NK cells. Cytotoxic function of NK cells was normal, and patients with infections had a significantly lower NK cell count than those without (p = 0.01). Patients with autoimmune manifestations had increased CD8 T-cell count. Proliferation of thymic precursors, as assessed by T-cell rearrangement excision circles, was increased. Six patients died (15%). CD4 T-cell count <150/mm and NK cell count <100/mm were predictors of death.In conclusion, ICL is a heterogeneous disorder often associated with deficiencies in CD8, CD19, and/or NK cells. Long-term prognosis may be related to initial CD4 and NK cell deficiency.

Idiopathic CD4 Lymphocytopenia: Spectrum of opportunistic infections, malignancies, and autoimmune diseases

Idiopathic CD4 lymphocytopenia (ICL) was first defined in 1992 by the US Centers for Disease Control and Prevention (CDC) as the repeated presence of a CD4+ T lymphocyte count of fewer than 300 cells per cubic millimeter or of less than 20% of total T cells with no evidence of human immunodeficiency virus (HIV) infection and no condition that might cause depressed CD4 counts. Most of our knowledge about ICL comes from scattered case reports. The aim of this study was to collect comprehensive data from the previously published cases to understand the characteristics of this rare condition. We searched the PubMed database and Science Direct for case reports since 1989 for Idiopathic CD4 lymphocytopenia cases. We found 258 cases diagnosed with ICL in 143 published papers. We collected data about age, sex, pathogens, site of infections, CD4 count, CD8 count, CD4:CD8 ratio, presence of HIV risk factors, malignancies, autoimmune diseases and whether the patients survived or died. The mean age at diagnosis of first opportunistic infection (or ICL if no opportunistic infection reported) was 40.7 ± 19.2 years (standard deviation), with a range of 1 to 85. One-sixty (62%) patients were males, 91 (35.2%) were females, and 7 (2.7%) patients were not identified whether males or females. Risk factors for HIV were documented in 36 (13.9%) patients. The mean initial CD4 count was 142.6 ± 103.9/mm³ (standard deviation). The mean initial CD8 count was 295 ± 273.6/mm³ (standard deviation). The mean initial CD4:CD8 ratio was 0.6 ± 0.7 (standard deviation). The mean lowest CD4 count was 115.4 ± 87.1/mm³ (standard deviation). The majority of patients 226 (87.6%) had at least one infection. Cryptococcal infections were the most prevalent infections in ICL patients (26.6%), followed by mycobacterial infections (17%), candidal infections (16.2%), and VZV infections (13.1%). Malignancies were reported in 47 (18.1%) patients. Autoimmune diseases were reported in 37 (14.2%) patients.

Successful fludarabine-based hematopoietic stem cell transplantation in a pediatric patient with idiopathic CD4+ lymphocytopenia

Idiopathic CD4+ lymphocytopenia (ICL) is a rare immunodeficiency disease with severe CD4 T-cell depletion, leading to serious opportunistic infections. The optimal treatment of ICL has not been determined, especially in severe form of the disease. Here, we report an eight-yr-old girl with ICL who was successfully treated with fludarabine-based conditioning HSCT. To the best of our knowledge, this is the first pediatric ICL case that was treated by HSCT. Allogeneic HSCT with a reduced intensity condition (RIC) regimen may be a feasible and curative treatment option in ICL patients with recurrent life-threatening complications.

Altered responses to homeostatic cytokines in patients with idiopathic CD4 lymphocytopenia

Idiopathic CD4 lymphocytopenia (ICL) is a rare immune deficiency characterized by a protracted CD4(+) T cell loss of unknown etiology and by the occurrence of opportunistic infections similar to those seen in AIDS. We investigated whether a defect in responses to cytokines that control CD4(+) T cell homeostasis could play a role in ICL. Immunophenotype and signaling responses to interleukin-7 (IL-7), IL-2, and thymic stromal lymphopoietin (TSLP) were analyzed by flow cytometry in CD4(+) T cells from 15 ICL patients and 15 healthy blood donors. The induction of phospho-STAT5 after IL-7 stimulation was decreased in memory CD4(+) T cells of some ICL patients, which correlated with a decreased expression of the IL-7Rα receptor chain (R = 0.74, p<0.005) and with lower CD4(+) T cell counts (R = 0.69, p<0.005). IL-2 responses were also impaired, both in the Treg and conventional memory subsets. Decreased IL-2 responses correlated with decreased IL-7 responses (R = 0.75, p<0.005), pointing to combined defects that may significantly perturb CD4(+) T cell homeostasis in a subset of ICL patients. Unexpectedly, responses to the IL-7-related cytokine TSLP were increased in ICL patients, while they remained barely detectable in healthy controls. TSLP responses correlated inversely with IL-7 responses (R = -0.41; p<0.05), suggesting a cross-regulation between the two cytokine systems. In conclusion, IL-7 and IL-2 signaling are impaired in ICL, which may account for the loss of CD4(+) T cell homeostasis. Increased TSLP responses point to a compensatory homeostatic mechanism that may mitigate defects in γc cytokine responses.

Long-term control of CMV retinitis in a patient with idiopathic CD4+ T lymphocytopenia

Cytomegalovirus (CMV) retinitis with idiopathic CD4(+) T lymphocytopenia (ICL) is rare and difficult to control. We report a first case for long-term control of CMV retinitis with ICL using interleukin-2 (IL-2) therapy and succeeded in discontinuation of anti-CMV therapy. A 49-year-old Japanese woman was diagnosed with ICL based on low CD4(+) count (72/μl), negative for HIV-1 and -2 antibodies, and absence of any defined immunodeficiency diseases or immunosuppressive therapy. PCR test of the aqueous humor in the right eye was suggestive of CMV retinitis. She was treated with systemic ganciclovir, but after several relapses of CMV retinitis, rhegmatogenous retinal detachment appeared in the right eye and she became blind in that eye. Three years later, she developed CMV retinitis in the left eye. Although she received systemic and focal anti-CMV treatments, the retinitis showed no improvement. Finally, retinal detachment occurred, and she underwent vitrectomy. IL-2 was injected to increase CD4(+) counts. Because of hyperpyrexia, blepharedema, central scotoma, and color anomaly, we changed to low-dose IL-2 therapy with no side effects. Finally, we succeeded in increasing the CD4(+) count to more than 200/μl after discontinuation of low-dose IL-2 therapy. CMV retinitis never recurred after discontinuation of anti-CMV therapy, with good visual acuity of 20/20 in the left eye. She developed blindness of the first affected right eye, whereas the visual acuity of the left eye remains excellent more than 12 years after the onset of CMV retinitis through the combined use of anti-CMV therapy, IL-2 therapy, and vitrectomy.

Idiopathic CD4 lymphocytopenia: a case of missing, wandering or ineffective T cells

Idiopathic CD4 lymphocytopenia (ICL) is a presumed heterogenous syndrome with key element low CD4 T-cell counts (below 300/mm³) without evidence of HIV infection or other known immunodeficiency. The etiology, pathogenesis, and management of ICL remain poorly understood and inadequately defined. The clinical presentation can range from serious opportunistic infections to incidentally diagnosed asymptomatic individuals. Cryptococcal and non-tuberculous mycobacterial infections and progressive multifocal leukoencephalopathy are the most significant presenting infections, although the spectrum of opportunistic diseases can be similar to that in patients with lymphopenia and HIV infection. Malignancy is common and related to opportunistic pathogens with an oncogenic potential. Autoimmune diseases are also seen in ICL with an increased incidence. The etiology of ICL is unknown. Mechanisms implicated in CD4 reduction may include decreased production, increased destruction, and tissue sequestration. New distinct genetic defects have been identified in certain patients with ICL, supporting the hypothesis of the lack of a common etiology in this syndrome. The management of ICL is focused on the treatment of opportunistic infections, appropriate prophylactic antibiotics, and close monitoring. In selected patients with life-threatening infections or profound immunodeficiency, strategies to increase T-cell counts or enhance immune function could be considered and have included interleukin-2, interferon-gamma, interleukin-7, and hematopoietic stem cell transplantation. The prognosis is influenced by the accompanying opportunistic infections and may be affected by publication bias of severe cases with unfavorable outcomes. As newer laboratory investigation techniques are being developed and targeted experimental treatments become available, our comprehension and prognosis of this rare syndrome could be significantly improved.

[Lymphocytopenia: aetiology and diagnosis, when to think about idiopathic CD4(+) lymphocytopenia?]

Une lymphopénie est définie par un nombre de lymphocytes circulants inférieur à 1500/mm³ chez l’adulte et 4500/mm³ chez l’enfant avant huit mois. La lymphopénie peut être globale ou sélective, affectant une population lymphocytaire particulière. Le diagnostic étiologique doit tenir compte de l’âge, du contexte, des manifestations clinicobiologiques associées et des thérapeutiques reçues. Les lymphopénies de l’adulte peuvent être liées schématiquement à : (1) une insuffisance de production (carence en zinc, corticothérapie, déficits immunitaires primitifs…), (2) un excès de catabolisme (radiothérapie, chimiothérapie, traitements immunosuppresseurs, infection par le VIH ou lupus systémique, etc.), (3) une modification de la répartition des lymphocytes (infections virales, choc septique, brûlures étendues, hypersplénisme, granulomatoses, etc.), (4) les étiologies multifactorielles ou non identifiées (insuffisance rénale chronique, certaines hémopathies lymphoïdes, tumeur solide, causes ethniques, etc.). Chez l’enfant, à ces étiologies s’ajoutent d’autres déficits immunitaires primitifs d’expression sévère (défaut des précurseurs thymiques, déficit cytokinique, défaut de synthèse des récepteurs des lymphocytes B et T et défaut de la transduction du signal ou des interactions cellulaires). La lymphopénie CD4⁺ idiopathique de l’adulte est un diagnostic d’élimination. Cette affection rare se définit par une lymphopénie T CD4⁺ inférieure ou égale à 300/mm³ ou inférieure ou égale à 20 % des lymphocytes totaux, persistante en l’absence de diagnostic alternatif. Elle peut être asymptomatique, s’associer à des infections à germes opportunistes, ou se compliquer de symptômes auto-immuns (en particulier cytopénies) ainsi que de néoplasies. Le traitement, calqué sur la prise en charge des patients infectés par le VIH, peut nécessiter le recours à une immunothérapie spécifique dont le bénéfice clinique reste à évaluer.

Defective T cell chemotaxis to sphingosine 1-phosphate and chemokine CCL21 in idiopathic T lymphocytopenia

T cell chemotaxis to sphingosine 1-phosphate (S1P) and the chemokines CCL21 and CCL5 was studied in ten adults with T lymphocytopenia, other immunological abnormalities (nine of ten), and frequent bacterial infections (seven of ten). Mean chemotactic responses to S1P of CD4 T cells from CD4 T lymphocytopenic patients and of CD8 T cells from CD8 T lymphocytopenic patients were significantly lower than those of healthy matched controls. Chemotaxis to CCL21 was lower than that of controls for CD4 T cells of three CD4 T lymphocytopenic patients and for CD8 T cells of three CD8 T lymphocytopenic patients, but none of the T cells of patients had diminished chemotaxis to CCL5. Defective T cell chemotactic responses to S1P and some chemokines may lead to subset-selective abnormal T cell trafficking and chronic T cell lymphocytopenia.

[Dysfunctions of the CXCL12 (SDF-1)/CXCR4 signaling axis in the WHIM syndrome and the idiopathic CD4(+) T-cell lymphocytopenia]

Chemokines are small cytokine-like secreted proteins that govern migration of leukocytes to their specific niches in lymphoid organs and to inflammatory sites. They mediate their functions by binding to and activating chemokine receptors, which belong to the heptahelical G protein-coupled receptor family. The CXC chemokine Stromal cell Derived Factor-1 (SDF-1/CXCL12) is the sole natural ligand for the broadly expressed CXCR4 receptor and acts as a chemoattractant for many leukocyte subsets. The CXCL12/CXCR4 axis exerts critical activities in homeostatic processes such as organogenesis, hematopoiesis and leukocyte trafficking. Dysregulations of CXCR4 signaling and/or expression are associated with several infectious, inflammatory, autoimmune and malignant conditions. In light of recent data, we review here CXCR4 dysfunctions unveiled in two rare human immunodeficiency disorders, one characterized by a gain of CXCR4 function, the WHIM syndrome, and the other by a loss of CXCR4 function, the idiopathic CD4(+) T-cell lymphocytopenia.

Case study documenting the diagnosis of idiopathic CD4+ Lymphocytopenia in a patient with atypical fungal infection (disseminated blastomycosis) by FNA of adrenal mass

Idiopathic CD4+ lymphocytopenia, described in 1992 by the Centers for Disease Control, is characterized by persistent CD4+ lymphocytopenia (less than 300 cells per micro-liter) in nonimmunosuppressed, HIV negative individuals, who present with atypical infections. This rare though likely undiagnosed entity is associated with chronic disseminated forms of either fungal or bacterial infections in otherwise healthy adults. We report a case of a 59-year-old male with ring-enhancing brain lesions, bilateral adrenal masses, lung and vocal cord nodules, where the diagnosis of exclusion was metastatic malignancy. Fine needle aspiration (FNA) of the adrenal mass and a subsequent vocal cord biopsy confirmed chronic widely disseminated blastomycosis. Flow cytometric evaluation of peripheral blood documented persistent selective CD4+ lymphocytopenia with T8 (suppressor) T-Lymphocyte count within normal range. We believe that idiopathic CD4+ lymphocytopenia is an important etiologic factor to be considered for patients who present with mass lesions and are diagnosed by FNA with atypical fungal infections. We relate the diagnostic criteria for idiopathic CD4+ lymphocytopenia and the importance of providing on-site triage for FNA samples for fungal studies and correlation for flow cytometry.