Margaret R. Brown

Pulmonary Nontuberculous Mycobacterial Disease: Prospective Study of a Distinct Preexisting Syndrome

RATIONALE Pulmonary nontuberculous mycobacterial (PNTM) disease is increasing, but predisposing features have been elusive. OBJECTIVES To prospectively determine the morphotype, immunophenotype, and cystic fibrosis transmembrane conductance regulator genotype in a large cohort with PNTM. METHODS We prospectively enrolled 63 patients with PNTM infection, each of whom had computerized tomography, echocardiogram, pulmonary function, and flow cytometry of peripheral blood. In vitro cytokine production in response to mitogen, LPS, and cytokines was performed. Anthropometric measurements were compared with National Health and Nutrition Examination Survey (NHANES) age- and ethnicity-matched female control subjects extracted from the NHANES 2001-2002 dataset. MEASUREMENTS AND MAIN RESULTS Patients were 59.9 (+/-9.8 yr [SD]) old, and 5.4 (+/-7.9 yr) from diagnosis to enrollment. Patients were 95% female, 91% white, and 68% lifetime nonsmokers. A total of 46 were infected with Mycobacterium avium complex, M. xenopi, or M. kansasii; 17 were infected with rapidly growing mycobacteria. Female patients were significantly taller (164.7 vs. 161.0 cm; P < 0.001) and thinner (body mass index, 21.1 vs. 28.2; P < 0.001) than matched NHANES control subjects, and thinner (body mass index, 21.1 vs. 26.8; P = 0.002) than patients with disseminated nontuberculous mycobacterial infection. A total of 51% of patients had scoliosis, 11% pectus excavatum, and 9% mitral valve prolapse, all significantly more than reference populations. Stimulated cytokine production was similar to that of healthy control subjects, including the IFN-gamma/IL-12 pathway. CD4(+), CD8(+), B, and natural killer cell numbers were normal. A total of 36% of patients had mutations in the cystic fibrosis transmembrane conductance regulator gene. CONCLUSIONS Patients with PNTM infection are taller and leaner than control subjects, with high rates of scoliosis, pectus excavatum, mitral valve prolapse, and cystic fibrosis transmembrane conductance regulator mutations, but without recognized immune defects.

Adult-onset immunodeficiency in Thailand and Taiwan

BACKGROUND Autoantibodies against interferon-γ are associated with severe disseminated opportunistic infection, but their importance and prevalence are unknown. METHODS We enrolled 203 persons from sites in Thailand and Taiwan in five groups: 52 patients with disseminated, rapidly or slowly growing, nontuberculous mycobacterial infection (group 1); 45 patients with another opportunistic infection, with or without nontuberculous mycobacterial infection (group 2); 9 patients with disseminated tuberculosis (group 3); 49 patients with pulmonary tuberculosis (group 4); and 48 healthy controls (group 5). Clinical histories were recorded, and blood specimens were obtained. RESULTS Patients in groups 1 and 2 had CD4+ T-lymphocyte counts that were similar to those in patients in groups 4 and 5, and they were not infected with the human immunodeficiency virus (HIV). Washed cells obtained from patients in groups 1 and 2 had intact cytokine production and a response to cytokine stimulation. In contrast, plasma obtained from these patients inhibited the activity of interferon-γ in normal cells. High-titer anti-interferon-γ autoantibodies were detected in 81% of patients in group 1, 96% of patients in group 2, 11% of patients in group 3, 2% of patients in group 4, and 2% of controls (group 5). Forty other anticytokine autoantibodies were assayed. One patient with cryptococcal meningitis had autoantibodies only against granulocyte-macrophage colony-stimulating factor. No other anticytokine autoantibodies or genetic defects correlated with infections. There was no familial clustering. CONCLUSIONS Neutralizing anti-interferon-γ autoantibodies were detected in 88% of Asian adults with multiple opportunistic infections and were associated with an adult-onset immunodeficiency akin to that of advanced HIV infection. (Funded by the National Institute of Allergy and Infectious Diseases and the National Institute of Dental and Craniofacial Research; ClinicalTrials.gov number, NCT00814827.).

Phase I Study of Recombinant Human Interleukin-7 Administration in Subjects with Refractory Malignancy

Purpose: Interleukin-7 (IL-7) has critical and nonredundant roles in T-cell development, hematopoiesis, and postdevelopmental immune functions as a prototypic homeostatic cytokine. Based on a large body of preclinical evidence, it may have multiple therapeutic applications in immunodeficiency states, either physiologic (immunosenescence), pathologic (HIV), or iatrogenic (postchemotherapy and posthematopoietic stem cell transplant), and may have roles in immune reconstitution or enhancement of immunotherapy. We report here on the toxicity and biological activity of recombinant human IL-7 (rhIL-7) in humans. Design: Subjects with incurable malignancy received rhIL-7 subcutaneously every other day for 2 weeks in a phase I interpatient dose escalation study (3, 10, 30, and 60 μg/kg/dose). The objectives were safety and dose-limiting toxicity determination, identification of a range of biologically active doses, and characterization of biological and, possibly, antitumor effects. Results: Mild to moderate constitutional symptoms, reversible spleen and lymph node enlargement, and marked increase in peripheral CD3+, CD4+, and CD8+ lymphocytes were seen in a dose-dependent and age-independent manner in all subjects receiving ≥10 μg/kg/dose, resulting in a rejuvenated circulating T-cell profile, resembling that seen earlier in life. In some subjects, rhIL-7 induced in the bone marrow a marked, transient polyclonal proliferation of pre-B cells showing a spectrum of maturation as well as an increase in circulating transitional B cells. Conclusion: This study shows the potent biological activity of rhIL-7 in humans over a well-tolerated dose range and allows further exploration of its possible therapeutic applications. Clin Cancer Res; 16(2); 727–35

Anti-IFN-γ Autoantibodies in Disseminated Nontuberculous Mycobacterial Infections

Although many patients with disseminated nontuberculous mycobacterial disease have molecular defects in the IFN-γ/IL-12 axis, recent case reports have shown autoantibodies against IFN-γ associated with severe nontuberculous mycobacterial infections. To check this finding in an independent population, we screened 35 patients with either disseminated or pulmonary nontuberculous mycobacterial infections for whom no molecular defect was known. We identified high-titer-neutralizing anti-IFN-γ IgG in the plasma of six patients. All six patients were female, parous, of East Asian descent, and had disseminated infection, predominantly with rapidly growing mycobacteria. The anti-IFN-γ IgG had in vitro biological activity on the IFN-γ-dependent phosphorylation of STAT-1 as well as on the IFN-γ-dependent up-regulation of TNF-α and IL-12. In contrast, this anti-IFN-γ Ab had no effect on IFN-α-dependent STAT-1 phosphorylation. These patients confirm a novel syndrome linking autoimmunity and immunodeficiency.

Measurement of T-cell CD69 expression: a rapid and efficient means to assess mitogen- or antigen-induced proliferative capacity in normals.

We have analyzed the expression of the activation antigen CD69 on normal human T cells by flow cytometry following stimulation with mitogens and recall antigen. These data were compared to parallel studies assessing the proliferative response using the 3H-thymidine (3H-TdR) incorporation assay. Three different mitogens (PHA, ConA, and CD2/CD2R) induced maximal expression of CD69 at 24 h, which remained stable throughout the 72 h culture period. The mitogen-stimulated cells initiated DNA synthesis as determined by the 3H-TdR assay (72 h) while nonstimulated cells failed to upregulate CD69 or incorporate 3H-TdR. We next compared T cell CD69 expression (n = 12) following stimulation with either CD2/CD2R (5 micrograms/ml) or the recall antigen, tetanus toxoid (1:1500). Cell proliferation was determined by the 3H-TdR assay at 72 h (CD2/CD2R) or 120 h (tetanus toxoid). Evaluation of CD69 expression at 6 h predicted CD2/CD2R but not tetanus responder status as defined by 3H-TdR incorporation. However, when 4 known tetanus responders (3H-TdR) were evaluated over time, it was found that at 48 h the fluorescence intensity (of CD69) on tetanus-stimulated CD3+ cells increased markedly compared with nonstimulated cells (range of increase 43-850%). One individual whose cells failed to respond to tetanus toxoid (3H-TdR and CD69) did respond normally to CD2/CD2R. These observations suggest that flow cytometric evaluation of T cell CD69 expression following mitogen (6 h) or antigen (48 h) stimulation may provide an accurate screen of T-cell responsiveness in normals.

Using biomarkers to predict the presence of FAS mutations in patients with features of the autoimmune lymphoproliferative syndrome

To the Editor: The autoimmune lymphoproliferative syndrome (ALPS) is characterized by chronic lymphadenopathy, splenomegaly, autoimmune cytopenias, and expansion of T cell receptor (TCR) αβ+ CD3+CD4−CD8− (αβ-double-negative [DNT]) cells (see this article’s Table E1 in the Online Repository at www.jacionline.org). Approximately two thirds of the patients with ALPS symptoms are genetically characterized, and most have germline (ALPS Ia) or somatic (ALPS Ia-s) TNFRSF6 (FAS) mutations. A small number of patients have defects in genes encoding Fas ligand (ALPS Ib), caspase-10 (ALPS II), or neuroblatoma-RAS (NRAS) viral oncogene homolog (ALPS IV). In addition, a large group of patients with ALPS findings remain genetically uncharacterized (ALPS III), and yet another has an undefined ALPS-like syndrome (ALPS-phenotype; Table I).1,2 Given the clinical similarities among all these groups, we sought to develop a biomarkers-based algorithm to predict the presence or absence of FAS mutations in this setting. TABLE I Description of patients with ALPS and control groups included in the study To this end, we investigated 26 parameters including immunophenotyping, eosinophil and monocyte counts, serum or plasma vitamin B12 (B12), soluble FAS ligand (sFASL), immunoglobulins, and levels of 14 cytokines in 562 subjects classified into 6 categories (Tables I and E1). The number of measurements, medians, and first and third quartiles are presented in this article’s Tables E2 and E3 in the Online Repository at www.jacionline.org. A full description of the Methods can be found in the Online Repository at www.jacionline.org. Elevated αβ-DNT cells are a hallmark of ALPS, but their utility for predicting FAS mutations had not been previously evaluated. 3 Patients with ALPS Ia and Ia-s had a high percentage of αβ-DNT cells, with median values 5.1% and 7.7%, respectively, compared with 0.5% for control mutation-negative relatives (MNRs; P 4% found in 60% (90/152) of patients with type Ia and in the majority of patients with type Ia-s (7/9), but in only 13% (11/85) of patients with ALPS type III and ALPS-phenotype (Fig 1, A). This value was associated with a positive likelihood ratio (LR) of 5.0 and a posttest probability of 89.3% for harboring FAS mutations. Conversely, the presence of αβ-DNT cells in the 1% to 2% range decreased the posttest probability to 25%, with a LR of 0.19 (Fig 2, B and C; see this article’s Table E4 in the Online Repository at www.jacionline.org). FIG 1 Biomarkers in patients with ALPS and control groups. Dashed lines represent cut-off values used to calculate likelihood ratios. Bars denote median values. P values for the differences between groups were obtained by Mann-Whitney test and are shown above ... FIG 2 sFASL levels and combinations of biomarkers accurately predict FAS mutations. A, Scatter plot showing sFASL levels. Increasing (B) and decreasing (C) probabilities for having a FAS mutation according to the percentage of αβ-DNT cells, ... In line with previous reports, patients with ALPS, regardless of mutation status, had 16% made the diagnosis of ALPS very unlikely (LR = 0.17). Other described abnormalities including increased CD3+HLA-DR+ to CD3+CD25+ ratio and high number of B cells had no additional diagnostic utility.4 We also evaluated serum B12 levels in patients with ALPS and found very elevated median levels in ALPS Ia and Ia-s (2259 ng/L; 1653 ng/L) compared with control MNRs (474 ng/L; P 1500 ng/L was 4.0, with a posttest probability of 87%. In contrast, having B12 levels <1000 ng/L diminished the posttest probability to 35% (Fig 2, B and C; Table E4). Analysis of plasma cytokines revealed 2 additional biomarkers for ALPS: IL-18 and TNF-α. Median plasma IL-18 levels were elevated in patients with ALPS Ia and Ia-s compared with control MNRs (1041 pg/mL, 1526 pg/mL, and 208 pg/mL, respectively; P < .0001). Patients with ALPS III and ALPS-phenotype had median values of 521 pg/mL and 702 pg/mL, respectively (P < .001 compared with MNRs; Fig 1, D). Furthermore, IL-18 <500 pg/mL was rarely seen in patients with ALPS and FAS mutations (7/56), with an associated negative LR of 0.19. TNF-α levels were higher in all ALPS groups with median values of 5 pg/mL for ALPS Ia (P < .0001), 9 pg/mL for ALPS Ia-s (P < .05), 8 pg/mL for ALPS III (P < .0001), and 7 pg/mL for ALPS-phenotype (P < .0001) compared with 1.3 pg/mL for MNRs (Fig 1, E). As previously reported, IL-10 was markedly elevated in ALPS Ia and Ia-s compared with MNRs (P 40 pg/mL, contrasting with 26% (10/38) of patients with ALPS III and ALPS-phenotype. For levels of IL-10 >40 ng/mL, the positive LR was 3.8, with a posttest probability of 85% for having a FAS mutation. Notably, only 20% (29/141) of patients with ALPS Ia and no patients with ALPS Ia-s had IL-10 values <20 pg/mL, giving a negative LR of 0.31 and a posttest probability of 33% for FAS mutations (Fig 2, B and C; Table E4). A recent report documented high levels of sFASL in patients with ALPS.7We expanded these findings analyzing more than 200 patients and controls. Ninety-seven percent of patients with ALPS Ia (136/140) and all patients with ALPS Ia-s had plasma sFASL >200 pg/mL, with median values of 1114 pg/mL and 1329 pg/mL, respectively, compared with control MNR levels of 104 pg/mL (P <.0001 for both groups). Only modest elevations of sFASL were seen in patients with ALPS III and ALPS-phenotype, as well as healthy mutation-positive relatives, with median values of 208 pg/mL, 174 pg/mL, and 207 pg/mL, respectively (Fig 2, A). These findings make sFASL the most sensitive biomarker to rule out a FAS mutation, with values <200 pg/mL associated with a negative LR of 0.05 and a posttest probability of 7.7% (Fig 2, C; Table E4). Soluble FASL also showed a strong positive correlation with IL-10 (r = 0.8;P < .0001) and a moderate correlation with αβ-DNTcells (r = 0.6; P < .0001) and B12 levels (r = 0.69; P < .0001; see this article’s Fig E1, A, in the Online Repository at www.jacionline.org). The area under the ROC curve for sFASL, αβ-DNT cells, B12, and IL-10 levels were calculated to evaluate how well they discriminate patients with a FAS mutation from those without (Fig E1, B). The area under the curve for sFASL was 0.9 (defines an excellent test) and for αβ-DNT cells was 0.81. B12 and IL-10 exhibited areas significantly less than sFASL (P < .05), with values of 0.76 and 0.77. We next evaluated whether combinations of αβ-DNT cells, B12, IL-10, IL-18, and sFASL would have increased power to predict or exclude FAS mutations in patients suspected of ALPS (Fig 2, B; Table E4). The combination of αβ-DNT cells >4% with B12 >1500 ng/L or IL-10 >40 pg/mL or IL-18 >500 ng/mL or sFASL >300 pg/mL was associated with >95% probability of having a FAS mutation. Conversely, having αβ-DNT cells <2% in combination with IL-10 <20 pg/mL or B12 <1000 ng/L or IL-18 <500 ng/mL decreased the probability of a FAS mutation to less than 10% (Fig 2, C; Table E4). Finally, finding αβ-DNT cells <2% and sFASL <200 pg/mL resulted in <2% probability for a FAS mutation. In conclusion, the biomarkers described should aid in the selection of patients with findings of ALPS for further diagnostic workup. In addition, the presence of a combination of markers strongly suggestive of a FAS mutation in the setting of a negative genetic test should prompt a search for somatic mutations in sorted αβ-DNT cells.

EBV-Related Lymphoproliferative Disease Complicating Therapy with the Anti-CD2 Monoclonal Antibody, Siplizumab, in Patients with T-Cell Malignancies

Purpose: We report an increased incidence of EBV-induced B-cell lymphoproliferative disease (LPD) in patients treated with siplizumab, an anti-CD2 antibody. The development of EBV-LPD has been associated with the use of immunosuppressive agents used in solid organ, bone marrow, and stem cell transplantation and in certain congenital immunodeficiencies. Experimental Design: We conducted a single-institution phase I dose-escalation trial of siplizumab, a humanized monoclonal antibody to CD2, in 29 patients with T-cell malignancies. Results: Although initial responses were encouraging, 4 (13.7%) patients developed EBV-LPD and the trial was stopped. Reductions in CD4+ and CD8+ cell count numbers in response to therapy were seen in all patients, but in those patients developing EBV-LPD a significantly greater reduction in natural killer (NK) cell number and CD2 expression on T cells was seen. These findings highlight the importance of NK-cell depletion and CD2 expression in addition to T-cell depletion in the etiology of EBV-LPD. Conclusions: The emergence of EBV-LPD may be associated with the ability of siplizumab to deplete both T and NK cells without affecting B cells. Agents that deplete T- and NK-cell populations without affecting B cell number should be screened for this potentially serious adverse event.

Patients with Chronic Granulomatous Disease Have a Reduced Peripheral Blood Memory B Cell Compartment

In this study, we have identified an altered B cell compartment in patients with chronic granulomatous disease (CGD), a disorder of phagocyte function, characterized by pyogenic infections and granuloma formation caused by defects in NADPH activity. This is characterized by an expansion of CD5-expressing B cells, and profound reduction in B cells expressing the memory B cell marker, CD27. Both findings were independent of the age, genotype, and clinical status of the patients, and were not accompanied by altered CD5 and CD27 expression on T cells. Focusing on CD27-positive B cells, considered to be memory cells based on somatically mutated Ig genes, we found that the reduction was not caused by CD27 shedding or abnormal retention of CD27 protein inside the cell. Rather, it was determined that CD27-negative B cells were, appropriately, CD27 mRNA negative, consistent with a naive phenotype, whereas CD27-positive B cells contained abundant CD27 mRNA and displayed somatic mutations, consistent with a memory B cell phenotype. Thus, it appears that CGD is associated with a significant reduction in the peripheral blood memory B cell compartment, but that the basic processes of somatic mutation and expression of CD27 are intact. X-linked carriers of CGD revealed a significant correlation between the percentage of CD27-positive B cells and the percentage of neutrophils with normal NADPH activity, reflective of the degree of X chromosome lyonization. These results suggest a role for NADPH in the process of memory B cell formation, inviting further exploration of secondary Ab responses in CGD patients.

Characterization of a Dipeptide Motif Regulating IFN-γ Receptor 2 Plasma Membrane Accumulation and IFN-γ Responsiveness

The IFN-γR complex is composed of two IFN-γR1 and two IFN-γR2 polypeptide chains. Although IFN-γR1 is constitutively expressed on all nucleated cells, IFN-γR2 membrane display is selective and tightly regulated. We created a series of fluorescent-tagged IFN-γR2 expression constructs to follow the molecule’s cell surface expression and intracellular distribution. Truncation of the receptor immediately upstream of Leu-Ile 255–256 (254X) created a receptor devoid of signaling that overaccumulated on the cell surface. In addition, this truncated receptor inhibited wild-type IFN-γR2 activity and therefore exerted a dominant negative effect. In-frame deletion (255Δ2) or alanine substitution (LI255–256AA) of these amino acids created mutants that overaccumulated on the plasma membrane, but had enhanced function. Single amino acid substitutions (L255A or I256A) had a more modest effect. In-frame deletions upstream (253Δ2), but not downstream (257Δ2), of Leu-Ile 255–256 also led to overaccumulation. A truncation within the IFN-γR2 Jak2 binding site (270X) led to a mutant devoid of function that did not overaccumulate and did not affect wild-type IFN-γR2 signaling. We have created a series of novel mutants of IFN-γR2 that have facilitated the identification of intracellular domains that control IFN-γR2 accumulation and IFN-γ responsiveness. In contrast to IFN-γR1, not only dominant negative, but also dominant gain-of-function, mutations were created through manipulation of IFN-γR2 Leu-Ile 255–256. These IFN-γR2 mutants will allow fine dissection of the role of IFN-γ signaling in immunity.