Fatal varicella zoster virus infection as first manifestation of idiopathic CD4+ T-cell lymphocytopenia

Administration of interleukin-7 increases CD4 T cells in idiopathic CD4 lymphocytopenia

Idiopathic CD4 lymphopenia (ICL) is a rare syndrome defined by low CD4 T-cell counts (<300/µL) without evidence of HIV infection or other known cause of immunodeficiency. ICL confers an increased risk of opportunistic infections and has no established treatment. Interleukin-7 (IL-7) is fundamental for thymopoiesis, T-cell homeostasis, and survival of mature T cells, which provides a rationale for its potential use as an immunotherapeutic agent for ICL. We performed an open-label phase 1/2A dose-escalation trial of 3 subcutaneous doses of recombinant human IL-7 (rhIL-7) per week in patients with ICL who were at risk of disease progression. The primary objectives of the study were to assess safety and the immunomodulatory effects of rhIL-7 in ICL patients. Injection site reactions were the most frequently reported adverse events. One patient experienced a hypersensitivity reaction and developed non-neutralizing anti-IL-7 antibodies. Patients with autoimmune diseases that required systemic therapy at screening were excluded from the study; however, 1 participant developed systemic lupus erythematosus while on study and was excluded from further rhIL-7 dosing. Quantitatively, rhIL-7 led to an increase in the number of circulating CD4 and CD8 T cells and tissue-resident CD3 T cells in the gut mucosa and bone marrow. Functionally, these T cells were capable of producing cytokines after mitogenic stimulation. rhIL-7 was well tolerated at biologically active doses and may represent a promising therapeutic intervention in ICL. This trial was registered at www.clinicaltrials.gov as #NCT00839436.

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.

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.

Complicated Varicella Infection at 8-year-old Boy with Pulmonary Agenesis

CONFLICT OF INTEREST: none declared.

Severe infections in HIV-exposed uninfected infants: clinical evidence of immunodeficiency

We describe the clinical and basic immunological findings of eight HIV-exposed uninfected infants hospitalized with serious infectious morbidity and referred for immunological evaluation. The median age at presentation was 5.5 (1.5-15) months. Infections included Pneumocystis jiroveci pneumonia (three), cytomegalovirus colitis with perforation (one), Pseudomonas sepsis (two), hemorrhagic varicella (one) and Group A streptococcal meningitis and endocarditis (one). Five required intensive care, four for assisted ventilation and one for post-surgical care. Follow-up to 36 months suggested resolution of a transient immunodeficiency in two infants, one of whom had CD4 and the other B-cell depletion. Further studies are indicated in HIV-exposed uninfected infants.

Idiopathic CD4 lymphocytopenia

PURPOSE OF REVIEW

A severe decrease of CD4 T cells predisposes humans to opportunistic infections. In adults, HIV is certainly the most common cause of CD4 lymphocytopenia, but other causes, such as infections, autoimmune diseases, immunosuppressive therapy, lymphoma and idiopathic forms need to be considered. This review summarizes the current knowledge of the poorly understood syndrome of idiopathic CD4 lymphocytopenia.

RECENT FINDINGS

Little research has tried to systematically dissect this probably heterogeneic syndrome after its initial description in 1992. Numerous cases presenting with opportunistic infections have been reported. Disturbed differentiation of stem cell precursors may contribute to CD4 lymphocytopenia. Because infections and lymphoma may also cause CD4 lymphocytopenia, the distinction between cause and effect may evolve only during follow-up.

SUMMARY

The manifestation of opportunistic infections calls for the evaluation of the immune system for CD4 lymphocytopenia. The differential diagnosis of this condition in adults comprises primarily HIV infection and less often other diseases or drugs. Idiopathic CD4 lymphocytopenia is very rare. The clinical significance of low CD4 cell counts in HIV negative patients still awaits its systematic analysis. Prophylaxis of opportunistic infections is oriented at the recommendations of HIV-infected individuals and causal treatment remains experimental.