Apoptosis of Peripheral CD4+ T-Lymphocytes in End-Stage Renal Disease Patients Under Hemodialysis and rhEPO Therapies

End-stage renal disease (ESRD) under hemodialyses (HD) is related with a higher propensity to infections, essentially due to T-cell lymphopenia. We postulated that HD procedure affects CD4⁺ T cells, especially by inducing apoptotic death and that recombinant human erythropoietin (rhEPO) therapy may also play an important role in the modulation of the immune system in these patients. T-cell phenotype and apoptosis of HD patients and healthy controls were evaluated by flow cytometry using anticoagulated whole-blood samples. In 12 HD patients, these parameters were also analyzed before and immediately after HD procedure. HD patients showed a decrease in total circulating CD3⁺ lymphocytes, especially in CD4⁺ T cells (0.747 ± 0.410 vs. 0.941 ± 0.216 × 10⁹/L, p < 0.05), which could be a consequence of the higher proportion of CD3⁺ and CD4⁺ lymphocytes in the latest stage of apoptosis (or death) and of the higher proportion of apoptotic CD4⁺ T cells observed in the patients immediately after HD procedure (2.91 ± 0.780 vs. 3.90 ± 1.96, p < 0.05). A positive and statistically significant correlation between CD3⁺ and CD4⁺ lymphocytes in latest stage of apoptosis (or death) with HD time was found (CD3⁺: r = 0.592, p < 0.01; CD4⁺: r = 0.501, p < 0.01). We also found a negative and significant correlation between weekly rhEPO doses and the number of CD4⁺ T cells (r = –0.358, p < 0.05). In conclusion, HD procedure still contributes to the development of T-cell lymphopenia, at least in part, by apoptosis induction. It was also shown that rhEPO therapy is associated with the CD4⁺ T-cell decline, possibly by immune modulation, eliminating atypical cells and helping to restore the CD4⁺ T-cell subset.     

Predicting progression to lymphoma in Sjögren's syndrome patients

Although the inherent complexity of the multifactorial nature of primary Sjögren's syndrome (pSS) renders the process of disease prognostication and prediction ambiguous, certain clinical and immunological characteristics have been described as lymphoma predictors in several studies. While the association between pSS and mucosa-associated lymphoid tissue lymphomas is indisputable, recent studies report a predominance of diffuse large B-cell lymphomas implying that pSS-lymphoma association is less subtype-specific than previously considered. The considerable differences in both disease severity and prognosis between patients with various types of lymphoma demand the identification of risk factors that can predict the development of the distinct subtypes. Additionally, a recently discovered diverse range of biological variables appears to influence clinical behavior and lymphoma outcome. In this review, we venture into the area of lymphoma prognostication in pSS, outlining long-established predictors, analyzing currently available prognostic models, and exploring the predictive potential of recent biological and molecular advances.     

Recent advances in understanding the pathogenesis and management of reticular dysgenesis

Reticular Dysgenesis is a rare immunodeficiency which is clinically characterized by the combination of Severe Combined Immunodeficiency (SCID) with agranulocytosis and sensorineural deafness. Mutations in the gene encoding adenylate kinase 2 (AK2) were identified to cause this phenotype. In this review, we will demonstrate important clinical differences between reticular dysgenesis and other SCID entities and summarize recent concepts in the understanding of the pathophysiology of the disease and the management strategies for this difficult condition.     

Treatment of idiopathic CD4 T lymphocytopenia with IL-2.

Idiopathic CD4 T lymphocytopenia (ICL) is an unusual immune defect in which there is an unexplained deficit of CD4 T cells, leading to fungal, parasitic or other serious opportunistic infections. Current treatment efforts are directed at eliminating infections. Here we describe the use of a novel treatment, subcutaneous polyethylene glycol (PEG)-IL-2 injections, in a woman with this disorder, who had chronic severe mycobacterial disease which led to repeated hospitalizations, and advancing respiratory insufficiency. For this patient, PEG-IL-2, 50 000 U/m2, has been given by weekly subcutaneous injections for 5.5 years. This treatment has resulted in marked (and still continuing) long-term immunological improvement with normalized T cell functions and increased CD4 cell numbers. She has had substantial clinical improvement with clearing of mycobacterial disease, reducing hospitalizations and improved lung functions. The improvement seen in this patient suggests that low-dose IL-2 is a safe and practical therapy, which might be useful in other subjects with this potentially serious immune defect.     

Pneumocystis pneumonia in brain tumor patients: risk factors and clinical features

Summary We reviewed the clinical features and risk factors for Pneumocystis carinii pneumonia (PCP) in patients with brain tumors (BTs) seen at our institution between 1980 and 1992. Previously rare, this opportunistic infection appears to be increasing among HIV-negative cancer patients receiving immunosuppressive medications. Recent reports have noted PCP among BT patients receiving corticosteroids, and suggested that these patients are particularly likely to develop PCP when corticosteroids are tapered.Nine BT patients, eight with high-grade gliomas, experienced ten episodes of PCP None were known HIV-positive. All were on dexamethasone (DXM) at PCP onset, and had continuously been receiving it for 47–398 days (median 69). Daily DXM dose at PCP onset ranged from 1–16 mg (median 9). Five episodes occurred in patients receiving a stable DXM dose and five during DXM taper. Nine episodes occurred in patients receiving chemotherapy. All patients had absolute lymphopenia at PCP onset, ranging from 80–900 × 10⁶ lymphocytes/l (median 222 × 10⁶/l, normal > 1000 × 10⁶). Three episodes were fatal despite appropriate antibiotic therapy.Unlike others, we did not find that corticosteroid taper predisposed to developing PCP As in HIV, PCP in BT patients appears related to lymphopenia, in these patients attributable to use and duration of corticosteroids and in some cases cytotoxic chemotherapy. Effective prophylaxis exists and should be considered for lymphopenic patients and those requiring DXM for > five weeks.     

Expression of the Ian family of putative GTPases during T cell development and description of an Ian with three sets of GTP/GDP-binding motifs

Reports suggest that two members of the novel immune-associated nucleotide (Ian) GTPase family, Ian1 and Ian5, play roles in T cell development. We performed real-time PCR analysis of the expression of Ian genes of the rat during T cell maturation, in macrophages and in cell lines. We found that all of the genes were expressed at relatively low levels at the early double-negative thymocyte stage but were expressed more strongly at later cell stages. Our study also revealed the fact that the previously reported Ian9, Ian10 and Ian11 genes are, instead, parts of a single gene for which we retain the name Ian9, potentially encoding a GTPase with a highly unusual triplicated structure. Antisera were developed against both Ian1 and Ian9. We established that Ian9 is produced as an approximately 75-kDa protein in both T cells and thymocytes. We observed that levels of both Ian1 and Ian9 proteins are profoundly reduced in T cells from lymphopenic rats as compared with wild-type rats. It was demonstrated that thymocytes and B cells from lymphopenic rats (Ian5 null) did not show enhanced sensitivity to gamma-irradiation-induced apoptosis.     

T cell-specific ablation of Fas leads to Fas ligand-mediated lymphocyte depletion and inflammatory pulmonary fibrosis

To study the role of Fas-Fas ligand (FasL) interaction-mediated apoptosis in lymphocyte homeostasis, we generated a mutant fas allele allowing conditional inactivation of the fas gene through Cre-mediated recombination. Experiments in which Fas was ablated in T cells, B cells, T and B cells, or in a more generalized manner demonstrated that the development of lymphoproliferative disease as seen in Fas-deficient mice requires Fas ablation in lymphoid and nonlymphoid tissues. Selective inactivation of Fas in T cells led to a severe lymphopenia over time, accompanied by up-regulation of FasL on activated T cells and apoptosis of peripheral lymphocytes. In addition, the mutant animals developed a fatal wasting syndrome caused by massive leukocyte infiltration in the lungs together with increased inflammatory cytokine production and pulmonary fibrosis. Inhibition of Fas-FasL interaction in vivo completely prevented the loss of lymphocytes and initial lymphocyte infiltration in the lungs. Thus, FasL-mediated interaction of activated, Fas-deficient T cells with Fas-expressing cells in their environment leads to break down of lymphocyte homeostasis and development of a lung disease strikingly resembling idiopathic pulmonary fibrosis in humans, a common and severe disease for which the mutant mice may serve as a first animal model.