Marco Marziali

Unravelling the Complexity of T Cell Abnormalities in Common Variable Immunodeficiency

We investigated several phenotypic and functional parameters of T cell-mediated immunity in a large series of common variable immunodeficiency (CVID) patients. We demonstrated that the vast majority of CVID patients presented multiple T cell abnormalities intimately related among them, the severity of which was reflected in a parallel loss of CD4+ naive T cells. A strong correlation between the number of CD4+ naive T cells and clinical features was observed, supporting the subgrouping of patients according to their number of naive CD4+ T lymphocytes. A reduced thymic output and disrupted CD4+ and CD8+ TCR repertoires paralleled the contraction of CD4+ naive T cell pools. The evaluation of activation markers and cytokine production indicated a strong T cell activation that was significantly related to the increased levels of T cell turnover and apoptosis. Finally, discrete genetic profiles could be demonstrated in groups of patients showing extremely diverse T cell subset composition and function. Naive CD4+ T cell levels were significantly associated with the switched memory B cell-based classification, although the concordance between the respective subgroups did not exceed 58.8%. In conclusion, our data highlight the key role played by the T cell compartment in the pathogenesis of CVID, pointing to the need to consider this aspect for classification of this disease.

T-cell homeostasis alteration in HIV-1 infected subjects with low CD4 T-cell count despite undetectable virus load during HAART.

Objective:To investigate the pathogenesis of low CD4 T-cell count in subjects who are immunological non responders (InR) to HAART. Design:Thirty-five HIV-positive subjects on HAART for at least 1 year, all with undetectable HIV-1 RNA, were studied. Patients were defined as InR according to a CD4 cell increase < 20% from CD4 cell baseline or CD4 cell count < 200/μl; subjects with a CD4 T-cell increase > 20% from baseline and a CD4 cell count > 200/μl were defined as immunological responders (IR). We performed a comprehensive study to characterize the immune response of InR. Methods:The immunological phenotype of peripheral blood mononuclear cells, thymic naive T cells, T-cell receptor Vβ repertoire, serum concentration of interleukin (IL)-7, the expression of IL-7Rα on naive and memory CD4 and CD8 T cells, and regulatory T cells (Treg) were studied. Results:In InR a significant reduction (P < 0.0001) of naive and thymic naive CD4 T cells was associated with a reduced expression of IL-7Rα in both cell subsets, with an increased serum concentration of IL-7 was observed. Furthermore, an increased immune activation with a reduced Treg frequency and increased number of expansions of Vβ families was observed. Conclusions:The reduced expression of IL-7Rα associated with the persistent immune activation and the alteration of Treg frequencies in part explains the low level of CD4 T cells observed in InR.

Purified T-depleted, CD34+ peripheral blood and bone marrow cell transplantation from haploidentical mother to child with thalassemia.

Fetomaternal microchimerism suggests immunological tolerance between mother and fetus. Thus, we performed primary hematopoietic stem cell transplantation from a mismatched mother to thalassemic patient without an human leukocyte antigen-identical donor. Twenty-two patients with thalassemia major were conditioned with 60 mg/kg hydroxyurea and 3 mg/kg azathioprine from day -59 to -11; 30 mg/m(2) fludarabine from day -17 to -11; 14 mg/kg busulfan starting on day -10; and 200 mg/kg cyclophosphamide, 10 mg/kg thiotepa, and 12.5 mg/kg antithymocyte globulin daily from day -5 to -2. Fourteen patients received CD34(+)-mobilized peripheral blood and bone marrow progenitor cells; 8 patients received marrow graft-selected peripheral blood stem cells CD34(+) and bone marrow CD3/CD19-depleted cells. T-cell dose was adjusted to 2 x 10(5)/kg by fresh marrow cell addback at the time of transplantation. Both groups received cyclosporine for graft-versus-host disease prophylaxis for 2 months after transplantation. Two patients died (cerebral Epstein-Barr virus lymphoma or cytomegalovirus pneumonia), 6 patients reject their grafts, and 14 showed full chimerism with functioning grafts at a median follow-up of 40 months. None of the 14 patients who showed full chimerism developed acute or chronic graft-versus-host disease. These results suggest that maternal haploidentical hematopoietic stem cell transplantation is feasible in patients with thalassemia who lack a matched related donor.

Novel pharmacokinetic behavior of intravenous busulfan in children with thalassemia undergoing hematopoietic stem cell transplantation: a prospective evaluation of pharmacokinetic and pharmacodynamic profile with therapeutic drug monitoring

We prospectively studied the pharmacokinetics (PK) and clinical outcomes of intravenous busulfan (Bu) in 71 children with preexisting liver damage who underwent hematopoietic stem cell transplantation for thalassemia. Intravenous Bu was administered every 6 hours as part of a conditioning regimen with PK-based dose adjustment to target a conservative area under the concentration-versus-time curve (AUC) range (900-1350 microMol*min). The first-dose Bu clearance (CL) was significantly higher than the subsequent daily CL that remained unchanged in the ensuing days. One-third of patients required dose escalation based on dose 1 AUC, whereas dose reduction was needed in the subsequent days. At doses 5, 9, and 13, 78%, 81%, and 87% of patients, respectively, achieved the target range of AUC. A population PK analysis confirmed that the first-dose CL was 20% higher and that body weight was the most important covariate to explain PK variability. Patients with variant GSTA1*B had a 10% lower Bu CL than wild-type. These results suggest that the disease-specific behavior of intravenous Bu PK should be considered for PK-guided dose adjustment in patients with thalassemia, and the use of a conservative AUC range resulted in low toxicity, good engraftment, and good survival rate.

Assessment of thymic output in common variable immunodeficiency patients by evaluation of T cell receptor excision circles

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by repeated infections and hypogammaglobulinaemia. Additionally, T‐cell abnormalities including lymphopenia, decreased proliferation to mitogens and antigens, and the reduced production and expression of cytokines, have also been observed. In this study we have investigated the expression of naive, memory and activation markers in T‐cell subpopulations in 17 CVID patients in comparison to age‐matched normal controls. The numbers of CD4+ T cells, including CD45RA+CD62L+ and, to a lesser extent, CD45RA–CD62L+/RA+CD62L– were significantly reduced in patients, whereas CD8+ T cells were within normal range. In contrast, HLA‐DR+ cells were increased both in CD4+ and CD8+ T cells. To assess the thymic output, we analysed the presence of T‐cell receptor excision circles (TRECs) in CD4+ and CD8+ T cells by quantitative PCR. TRECs were decreased significantly in patients and the rate of TREC loss was higher with increasing age. TRECs correlated with naive CD4+ T cells, whereas there was an inverse relationship between TRECs and CD8+HLA–DR+ and CD8+CD45RA–CD62L+/RA+CD62L– T cells. Our results suggest the presence of a defect in the naive T cell compartment with origin at the thymic level in CVID, and indicate that TREC may be a useful marker to monitor thymic function in this primary immunodeficiency.

Biased T-cell receptor repertoires in patients with chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome)

Chromosome 22q11.2 deletion (del22q11.2) syndrome (DiGeorge syndrome/velocardiofacial syndrome) is a common syndrome typically consisting of congenital heart disease, hypoparathyroidism, developmental delay and immunodeficiency. Although a broad range of immunologic defects have been described in these patients, limited information is currently available on the diversity of the T‐cell receptor (TCR) variable β (BV) chain repertoire. The TCRBV repertoires of nine patients with del22q11.2 syndrome were determined by flow cytometry, fragment size analysis of the third complementarity determining region (CDR3 spectratyping) and sequencing of V(D)J regions. The rate of thymic output and the phenotype and function of peripheral T cells were also studied. Expanded TCRBV families were detected by flow cytometry in both CD4+ and CD8+ T cells. A decreased diversity of TCR repertoires was also demonstrated by CDR3 spectratyping, showing altered CDR3 profiles in the majority of TCRBV families investigated. The oligoclonal nature of abnormal peaks detected by CDR3 spectratyping was confirmed by the sequence analysis of the V(D)J regions. Thymic output, evaluated by measuring TCR rearrangement excision circles (TRECs), was significantly decreased in comparison with age‐matched controls. Finally, a significant up‐regulation in the percentage, but not in the absolute count, of activated CD4+ T cells (CD95+, CCR5+, HLA‐DR+), IFN‐γ ‐ and IL‐2‐expressing T cells was detected. These findings suggest that the diversity of CD4 and CD8 TCRBV repertoires is decreased in patients with del22q11.2 syndrome, possibly as a result of either impaired thymic function and/or increased T‐cell activation.

Late-Onset Hemorrhagic Cystitis in Children after Hematopoietic Stem Cell Transplantation for Thalassemia and Sickle Cell Anemia: A Prospective Evaluation of Polyoma (BK) Virus Infection and Treatment with Cidofovir

Little is known about late-onset hemorrhagic cystitis (HC) in children, its relationship to BK virus, and treatment with cidofovir (CDV) following hematopoietic stem cell transplantation (HSCT). We prospectively investigated BK virus reactivation in children who underwent HSCT from a matched related donor for thalassemia or sickle cell anemia following busulfan-cyclophosphamide-based conditioning regimens and analyzed risk factors for development of HC and its treatment with CDV. Grade 2-4 HC occurred in 30 patients with a cumulative incidence of 26% (95% confidence interval [CI] = 18%-34%). The cumulative incidences of BK viruria and viremia were 81% (95% CI = 69%-89%) and 28% (95% CI = 18%-40%), respectively. Multivariate analysis revealed that use of antithymocyte globulin (ATG) (hazard ratio [HR] = 10.5; P = .001), peak BK viruria >100,000 copies/mL (HR = 6.2; P = .004), and grade II-IV acute graft-versus-host disease (HR = 5.3; P = .007) were predictive factors for HC. Nineteen patients with HC were given CDV at 1.5 mg/kg/day 3 times a week, or 5 mg/kg/week. The median duration of therapy was 27 days (range, 21-180 days), and a median of 9 doses were given (range, 6-22). All patients had a complete clinical response (CCR), and 69% had a microbiological response at 4 weeks. Eleven patients with BK virus-related HC receiving supportive care also had CCR. The median duration of HC in these patients was similar to that in patients treated with CDV. None of the patients with HC cleared BK viruria when CCR was achieved. We conclude that late-onset HC is more prevalent in children with sustained high BK viruria who are treated with ATG or who develop graft-versus-host disease. Randomized clinical trials are urgently needed to better define the role of CDV in treating BK virus-related HC.

Bone Marrow Clonogenic Capability, Cytokine Production, and Thymic Output in Patients with Common Variable Immunodeficiency

In patients with primary Ab deficiencies, hematological and immunological abnormalities are frequently observed. A regenerative failure of hemopoietic stem/progenitor cells has been hypothesized. We evaluated in the bone marrow (BM) of 11 patients with common variable immunodeficiency, the phenotype of BM progenitors and their in vitro growth by colony-forming cell (CFC) and long-term culture (LTC) assays. A significant decrease in erythroid and mixed CFC and, to a greater extent, in primitive LTC-CFC progenitors was observed in patients compared with healthy controls. The frequency of BM pre-B and pro-B cells correlated directly with the absolute number of CD19+ lymphocytes. BM cells cultured in vitro produced spontaneously lower amounts of IL-2 and elevated levels of TNF-α compared with controls, indicating a skewing toward a proapoptotic cytokine pattern. In addition, stromal cells generated after BM LTC secreted less IL-7 and displayed by immunohistochemistry an altered phenotype. These findings were associated with a significant decrease in naive Th cells coexpressing CD31 in the peripheral blood. These results indicate an impaired growth and differentiation capacity of progenitor cells in patients with common variable immunodeficiency.

T cell responses to highly active antiretroviral therapy defined by chemokine receptors expression, cytokine production, T cell receptor repertoire and anti-HIV T-lymphocyte activity

The immunological correlates of highly active antiretroviral therapy (HAART)‐induced suppression of human immunodeficiency virus type 1 (HIV‐1) replication have been investigated.

Changes in CCR5 and CXCR4 expression and β-chemokine production in HIV-1-infected patients treated with highly active antiretroviral therapy

&NA; The effect of highly active antiretroviral therapy (HAART) on the expression of CCR5 and CXCR4 HIV coreceptors and the production of the &bgr;‐chemokines regulated upon activation, normal T‐cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)‐1&agr;, and MIP‐1&bgr; has been investigated in 30 HIV‐1‐infected individuals during 12‐36 months of therapy. CCR5 expression was increased in both CD4+ and CD8+ subsets, whereas CXCR4 expression was upregulated only in CD4+ cells. CCR5 levels normalized during 36 months of therapy and positively correlated with the levels of memory, CD95+, and HLA‐DR+ T cells. In contrast, the frequency of CXCR4‐expressing cells was not significantly modified by HAART, although a downregulation was observed early after starting treatment. CXCR4 levels were significantly associated with the frequencies of naive T cells and negatively correlated with plasma viral load, CD95, and HLA‐DR expression. An increased production of both spontaneous and lectin‐induced RANTES, MIP‐1&agr;, and MIP‐1&bgr; was found at baseline in HIV‐infected individuals. The spontaneous &bgr;‐chemokines production was not modified by 12 months of HAART, although a significant reduction was seen during the first months of therapy. A transient decrease of lectinstimulated RANTES production was also observed, whereas the reduction of lectininduced MIP‐1&agr; persisted for up to 12 months of therapy. In contrast, MIP‐1&bgr; secreted by phytohemagglutinin antigen‐stimulated peripheral blood mononuclear cells progressively increased during HAART. In conclusion, our data indicate a normalization of CCR5 but not CXCR4 expression during suppressive therapy and changes in &bgr;‐chemokine production that may play a part in dictating the efficiency of viral infection and consequently the disease course.