"Borderline" idiopathic CD4+ T-cell lymphocytopenia presenting with atypical progressive multifocal leukoencephalopathy.

Idiopathic CD4+ lymphocytopenia (ICL) is a rare disorder characterized by low counts of CD4+ cells (<300/mm3) in absence of other known causes of immunosuppression. A few cases of progressive multifocal leukoencephalopathy (PML) were reported in association with ICL with variable outcome. We describe the case of a 40 year-old man diagnosed with PML, which showed a monophasic course. Causes of primary and secondary immunodeficiency were ruled out, only a "borderline" ICL was found. This case highlights that a severe immunodepression could not be an absolute prerequisite in developing PML and also points the attention on current definition of ICL.

Prevalence and pathogenicity of autoantibodies in patients with idiopathic CD4 lymphopenia.

BACKGROUNDIdiopathic CD4 lymphopenia (ICL) is defined by persistently low CD4+ cell counts (<300 cells/µL) in the absence of a causal infection or immune deficiency and can manifest with opportunistic infections. Approximately 30% of ICL patients develop autoimmune disease. The prevalence and breadth of their autoantibodies, however, and their potential contribution to pathogenesis of ICL remain unclear.METHODSWe hybridized 34 and 51 ICL patients' sera to a 9,000-human-proteome array and to a 128-known-autoantigen array, respectively. Using a flow-based method, we characterized the presence of anti-lymphocyte Abs in the whole cohort of 72 patients, as well as the Ab functional capability of inducing Ab-dependent cell-mediated cytotoxicity (ADCC), complement deposition, and complement-dependent cytotoxicity (CDC). We tested ex vivo the activation of the classical complement pathway on ICL CD4+ T cells.RESULTSAll ICL patients had a multitude of autoantibodies mostly directed against private (not shared) targets and unrelated quantitatively or qualitatively to the patients' autoimmune disease status. The targets included lymphocyte intracellular and membrane antigens, confirmed by the detection by flow of IgM and IgG (mostly IgG1 and IgG4) anti-CD4+ cell Abs in 50% of the patients, with half of these cases triggering lysis of CD4+ T cells. We also detected in vivo classical complement activation on CD4+ T cells in 14% of the whole cohort.CONCLUSIONOur data demonstrate that a high prevalence of autoantibodies in ICL, some of which are specific for CD4+ T cells, may contribute to pathogenesis, and may represent a potentially novel therapeutic target.TRIAL REGISTRATIONClinicalTrials.gov NCT00867269.FUNDINGNIAID and National Institute of Arthritis and Musculoskeletal and Skin Diseases of the NIH.

Idiopathic CD4+ T lymphocytopenia: A case report.

Idiopathic CD4+ T lymphocytopenia (ICL) is a very rare immunodeficiency syndrome with an unexplained depletion of CD4+ T lymphocytes and no evidence of Human Immunodeficiency Virus (HIV) infection. Here we report a 29-year-old male patient who had severe ulcerative colitis with low level CD4+ count of 254 cells/mm3, and had no evidence of HIV or Human T cell Lymphotrophic virus type I or II infections. He had recurrent Candidiasis infection and his CD4 count was just 53 cells/mm3 after 3 months. The cause for the decline of CD4 T lymphocytes was unknown.

Humanized mouse models reveal an immunologic classification of idiopathic CD4 lymphocytopenia subtypes.

Idiopathic CD4 lymphocytopenia (ICL) is a clinically heterogeneous immunodeficiency disorder defined by low numbers of circulating CD4+ T cells and increased susceptibility to opportunistic infections. CD8+ T cells, NK, and/or B cells may also be deficient in some patients. To delineate possible pathogenic cellular mechanisms in ICL, we compared immune system development and function in NOD-RAGKO-γcKO (NRG) mice transplanted with hematopoietic stem cells from patients with ICL or healthy controls. CD34+ hematopoietic stem cells from healthy controls and patients with ICL reconstituted NRG mice equally well. In contrast, PBMC transfers into NRG mice identified 2 ICL engraftment phenotypes, reconstituting and nonreconstituting (NR), based on the absence or presence of donor lymphopenia. For patients in the NR group, the distribution of lymphocyte subsets was similar in the peripheral blood of both the patient and the corresponding humanized mice. The NR-ICL group could be further divided into individuals whose CD3+ T cells had defects in proliferation or survival. Thus, ICL cellular pathogenesis might be classified by humanized mouse models into 3 distinct subtypes: (a) T cell extrinsic, (b) T cell intrinsic affecting proliferation, and (c) T cell intrinsic affecting survival. Humanized mouse models of ICL help to delineate etiology and ultimately to guide development of individualized therapeutic strategies.

Idiopathic CD4 Lymphocytopenia.

We report a 42 year old male who was an interesting case of "idiopathic CD4 lymphocytopenia"(ICL) in a non-HIV adult with-extra pulmonary tuberculosis along with the diffuse splenic calcification and whose symptoms improved with Antitubercular treatment. He was found to have low CD4 counts on two occasions.

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.

Unusual and severe disease course in a child with ataxia-telangiectasia.

Ataxia-telangiectasia (AT) is an autosomal recessive syndrome of combined immunodeficiency. Hallmarks of the disease comprise progressive cerebellar ataxia, oculocutaneous telangiectasia, cancer susceptibility and variable humoral and cellular immunodeficiency. We describe a patient with AT presenting with autoimmune haemolytic anaemia, neutropenia, hepatosplenomegaly, lymphadenopathy and hyper-IgM at the age of 6 months. At the age of 26 months she developed persistent fever, progressive lymphadenopathy and pulmonary nodular infiltrates, which were responsive to steroid therapy.

[Late onset immunodeficiency with hypo-IgG and hyper-IgM, T CD4+ lymphocytopenia and vitiligo]. / Immunodeficienza ad insorgenza tardiva con ipo-IgG e iper-IgM, linfocitopenia T CD4+ e vitiligo.

The Authors report the clinical case of a patient with a deficit of humoral immunity who developed infections since puberty. The serum levels of IgG and IgA decreased progressively in the fourth decade of life, while serum IgM increased. Moreover, the patient developed a marked CD4+ T lymphocytopenia and a meager B lymphocytopenia, vitiligo, positivity for anti-SSA/Ro autoantibodies and granulomatous phlogosis of the knee. The heterogeneity of the clinical and laboratory data suggests that this patient might present an overlap immunodeficiency syndrome with some of the clinical and immunological features typical of the hyper-IgM syndrome (in the X-linked or autosomal forms) and others that can be referred to a nosologically distinct humoral immunodeficiency such as the common variable immunodeficiency.

Characterization of gammadelta T cells expressing CD158b, a killer cell inhibitory receptor, in a patient with chronic CD4(+) lymphocytopenia and disseminated Mycobacterium intracellulare infection.

A population of Vdelta1(+)Vgamma9(-) gammadelta T cells that represented almost the totality (84%) of circulating lymphocytes in a patient with chronic, non-HIV-related, CD4 lymphocytopenia complicated by a disseminated Mycobacterium intracellulare infection was characterized. These gammadelta(+) T cells expressed a single killer inhibitory receptor (CD158b) and their phenotype (CD8(+)CD57(+)CD27(-)CD28(-)) indicated that, although CD45RA(+), they were not naive. However, the absence of large granular lymphocyte morphology, the impaired proliferative activity, the high susceptibility to apoptosis, and the total lack of cytotoxic ability suggested that these gammadelta cells were in a resting state. A high percentage of the cells did not harbor the CD11b integrin alpha chain and exhibited a decreased capability to bind endothelial cells. This defect might represent the mechanism whereby they remained trapped in the circulation.