Altered responses to homeostatic cytokines in patients with idiopathic CD4 lymphocytopenia

Successful Cord Blood Transplantation for Idiopathic CD4+ Lymphocytopenia

Idiopathic CD4+ lymphocytopenia (ICL) is the depletion of CD4+ lymphocytes to <300 cells/mm3 without human immunodeficiency virus infection or other causes of lymphocytopenia. ICL causes fatal infections; its etiology remains unclear and it lacks consensus regarding therapeutic options. We report the first patient with ICL who had a successful clinical course following a cord blood transplant (CBT). A 45-year-old woman was diagnosed with ICL and underwent partial hepatectomy for an abscess caused by the Mycobacterium avium complex. No specific gene alterations were detected through next generation sequencing-based evaluation. Following a reduced-intensity conditioning (RIC) regimen consisting of fludarabine, busulfan, and 4 Gy total body irradiation, a single-unit CBT was performed. Neutrophils were engrafted on day +14. CD4+ lymphocyte counts increased to over 300 cells/mm3 on day +436. After 75 months, she was alive without any sequelae. CBT with an RIC regimen could be a curable treatment option for ICL.

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.

Idiopathic CD4 T Cell Lymphocytopenia: A Case of Overexpression of PD-1/PDL-1 and CTLA-4

Idiopathic CD4 T cell lymphocytopenia (ICL) is a rare entity characterized by CD4 T cell count of <300 cells/mm³ along with opportunistic infection for which T cell marker expression remains to be fully explored. We report an ICL case for which T lymphocyte phenotype and its costimulatory molecules expression was analyzed both ex vivo and after overnight stimulation through CD3/CD28. The ICL patient was compared to five healthy controls. We observed higher expression of inhibitory molecules PD-1/PDL-1 and CTLA-4 on CD4 T cells and increased regulatory T cells in ICL, along with high activation and low proliferation of CD4 T cells. The alteration in the expression of both the costimulatory pathway and the apoptotic pathway might participate to down-regulate both CD4 T cell functions and numbers observed in ICL.

A Panoply of Rheumatological Manifestations in Patients with GATA2 Deficiency

Purpose: To characterize rheumatological manifestations of GATA2 deficiency. Methods: Single-center, retrospective review of 157 patients with GATA2 deficiency. Disease course, laboratory results, and imaging findings were extracted. In-person rheumatological assessments were performed on selected, available patients. A literature search of four databases was conducted to identify additional cases. Results: Rheumatological findings were identified in 28 patients, out of 157 cases reviewed (17.8%). Twenty-two of those patients (78.6%) reported symptom onset prior to or in conjunction with the molecular diagnosis of GATA2 deficiency. Notable rheumatological manifestations included: piezogenic pedal papules (PPP), joint hyperextensibility, early onset osteoarthritis, ankylosing spondylitis, and seronegative erosive rheumatoid arthritis. In peripheral blood of patients with rheumatological manifestations and GATA2 deficiency, CD4+ CD3+ helper T cells and naïve CD3+ CD4+ CD62L+ CD45RA+ helper T cell subpopulation fractions were significantly lower, while CD8+ cytotoxic T cell fractions were significantly higher, compared to those without rheumatological manifestations and with GATA2 deficiency. No changes in CD19, CD3, or NK populations were observed. Conclusion: GATA2 deficiency is associated with a broad spectrum of rheumatological disease manifestations. Low total helper T lymphocyte proportions and low naïve helper T cell proportions are associated with those most at risk of overt rheumatological manifestations. Further, PPP and joint hyperextensibility may explain some of the nonimmunologically-mediated joint problems encountered in patients with GATA2 deficiency. This catalogue suggests that rheumatological manifestations and immune dysregulation are relatively common in GATA2 deficiency.

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.

Human naïve regulatory T-cells feature high steady-state turnover and are maintained by IL-7

Naïve FoxP3-expressing regulatory T-cells (Tregs) are essential to control immune responses via continuous replenishment of the activated-Treg pool with thymus-committed suppressor cells. The mechanisms underlying naïve-Treg maintenance throughout life in face of the age-associated thymic involution remain unclear. We found that in adults thymectomized early in infancy the naïve-Treg pool is remarkably well preserved, in contrast to conventional naïve CD4 T-cells. Naïve-Tregs featured high levels of cycling and pro-survival markers, even in healthy individuals, and contrasted with other circulating naïve/memory CD4 T-cell subsets in terms of their strong γc-cytokine-dependent signaling, particularly in response to IL-7. Accordingly, ex-vivo stimulation of naïve-Tregs with IL-7 induced robust cytokine-dependent signaling, Bcl-2 expression, and phosphatidylinositol 3-kinase (PI3K)-dependent proliferation, whilst preserving naïve phenotype and suppressive capacity. Altogether, our data strongly implicate IL-7 in the thymus-independent long-term survival of functional naïve-Tregs, and highlight the potential of targeting the IL-7 pathway to modulate Tregs in different clinical settings.

Idiopathic CD4 T-Cell Lymphocytopenia: A Case Report of a Young Boy With Recalcitrant Warts

IMPORTANCE

Idiopathic CD4 T-cell lymphocytopenia (ICL) is an immunodeficiency disorder that presents with a decrease in CD4(+) T cells without evidence of a human immunodeficiency virus infection. It is most commonly diagnosed after a patient presents with an opportunistic infection and can also be associated with malignancies and autoimmune diseases. This case presentation and literature review highlights the common skin findings in patients with ICL, mainly recalcitrant warts, and discusses the treatment options available.

OBSERVATIONS

The patient described is the youngest reported with ICL presenting with isolated cutaneous findings of recalcitrant warts and psoriasis. Many treatment options were tried for the warts, with the most significant response to acitretin.

CONCLUSIONS AND RELEVANCE

This case highlights the importance of considering underlying immunodeficiency in patients with recalcitrant warts as well as developing treatment plans. Such patients require close follow-up by both dermatology and immunology to monitor for the development of other diseases related to ICL.

Syndrome of selective IgM deficiency with severe T cell deficiency associated with disseminated cutaneous mycobacterium avium intracellulaire infection

Cutaneous non-disseminated, non-tuberculous mycobacterial infections have been reported in both immunocompetent and immunocompromised subjects. Systemic Mycobacterium avium intracellulaire (MAI) have been reported in non-HIV patients with Idiopathic CD4 lymphocytopenia. We report a comprehensive immunological analysis in syndrome of selective IgM deficiency and T lymphocytopenia (both CD4+ and CD8+) with disseminated cutaneous MAI infection. Naïve (TN) and Central memory (TCM) subsets of both CD4+ and CD8+ T cells were decreased, whereas terminally differentiated effector memory (TEMRA) subset of CD4+ and CD8+ T cells were markedly increased. IFN-γ producing T cells were markedly decreased. Although CD14(high)CD16- proinflammatory monocytes were modestly increased, IFN-γR+ monocytes were markedly decreased. The expression of TLR3, TLR5, TLR7, and TLR9 on monocytes was decreased. Germinal center B cells (CD19+IgD-CD38+CD27(lo)) and B1 cells (CD20+CD27+CD43+CD70-) were markedly decreased. A role of immune alterations, including B cells and antibodies in disseminated cutaneous MAI infection is discussed.

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.

DUSP4-mediated accelerated T-cell senescence in idiopathic CD4 lymphopenia

Idiopathic CD4 lymphopenia (ICL) is a rare heterogeneous immunological syndrome of unclear etiology. ICL predisposes patients to severe opportunistic infections and frequently leads to poor vaccination effectiveness. Chronic immune activation, expansion of memory T cells, and impaired T-cell receptor (TCR) signaling have been reported in ICL, but the mechanistic and causative links remain unclear. We show that late-differentiated T cells in 20 patients with ICL displayed defective TCR responses and aging markers similar to those found in T cells from elderly subjects. Intrinsic T-cell defects were caused by increased expression of dual-specific phosphatase 4 (DUSP4). Normalization of DUSP4 expression using a specific siRNA improved CD4(+) T-cell activity in ICL, as this restored TCR-induced extracellular signal-regulated kinase activation and increased the expression of the costimulatory molecules CD27 and CD40L. Conversely, repeated TCR stimulation led to defective signaling and DUSP4 overexpression in control CD4(+) T cells. This was associated with gradual acquisition of a memory phenotype and was curtailed by DUSP4 silencing. These findings identify a premature T-cell senescence in ICL that might be caused by chronic T-cell activation and a consequential DUSP4-dependent dampening of TCR signaling.