Primary Effusion Lymphoma (PEL)-Like Lymphoma in a Child With Congenital Immunodeficiency

Primary effusion lymphoma (PEL) is a rare lymphoma that occurs more frequently in immunocompromised adults and has a poor survival. We report a 9-year-old female with combined immunodeficiency with an Epstein-Barr virus positive/human herpes virus 8 negative PEL-like lymphoma. The treatment with systemic chemotherapy for non-Hodgkin lymphoma, zidovudine, and interferon-α failed to control disease progression. This is the first reported pediatric case of PEL-like lymphoma. Increased diagnostic awareness and more effective treatment strategies are needed for this rare lymphoma.

Broad-spectrum antibodies against self-antigens and cytokines in RAG deficiency

Patients with mutations of the recombination-activating genes (RAG) present with diverse clinical phenotypes, including severe combined immune deficiency (SCID), autoimmunity, and inflammation. However, the incidence and extent of immune dysregulation in RAG-dependent immunodeficiency have not been studied in detail. Here, we have demonstrated that patients with hypomorphic RAG mutations, especially those with delayed-onset combined immune deficiency and granulomatous/autoimmune manifestations (CID-G/AI), produce a broad spectrum of autoantibodies. Neutralizing anti-IFN-α or anti-IFN-ω antibodies were present at detectable levels in patients with CID-G/AI who had a history of severe viral infections. As this autoantibody profile is not observed in a wide range of other primary immunodeficiencies, we hypothesized that recurrent or chronic viral infections may precipitate or aggravate immune dysregulation in RAG-deficient hosts. We repeatedly challenged Rag1S723C/S723C mice, which serve as a model of leaky SCID, with agonists of the virus-recognizing receptors TLR3/MDA5, TLR7/-8, and TLR9 and found that this treatment elicits autoantibody production. Altogether, our data demonstrate that immune dysregulation is an integral aspect of RAG-associated immunodeficiency and indicate that environmental triggers may modulate the phenotypic expression of autoimmune manifestations.

Characteristic scapular and rib changes on chest radiographs of children with ADA-deficiency SCIDS in the first year of life

BACKGROUND

We describe radiographic changes in the ribs and scapulae seen in the first 6 months of life in children with ADA (adenosine deaminase) deficiency severe combined immundeficiency syndrome (SCIDS). We suggest that these changes are reversible with appropriate enzyme replacement therapy.

OBJECTIVE

The purpose of this study was to describe characteristic rib and scapular radiographic changes in infants with ADA-deficiency SCIDS.

MATERIALS AND METHODS

This was a retrospective review of chest radiographs of nine children with ADA-deficiency SCIDS performed in the first year of life by two experienced pediatric radiologists. A control cohort of unaffected children was used for comparison.

RESULTS

All children with ADA-deficiency SCIDS manifested unusual scapular spurring and anterior rib cupping. None of the control children manifested these changes.

CONCLUSION

Characteristic and reversible scapular and rib changes in the correct clinical setting should suggest an early diagnosis of ADA deficiency, prompting appropriate diagnostic and therapeutic measures.

Clinical features and outcome of patients with IRAK-4 and MyD88 deficiency

Autosomal recessive interleukin-1 receptor-associated kinase (IRAK)-4 and myeloid differentiation factor (MyD)88 deficiencies impair Toll-like receptor (TLR)- and interleukin-1 receptor-mediated immunity. We documented the clinical features and outcome of 48 patients with IRAK-4 deficiency and 12 patients with MyD88 deficiency, from 37 kindreds in 15 countries.The clinical features of IRAK-4 and MyD88 deficiency were indistinguishable. There were no severe viral, parasitic, and fungal diseases, and the range of bacterial infections was narrow. Noninvasive bacterial infections occurred in 52 patients, with a high incidence of infections of the upper respiratory tract and the skin, mostly caused by Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The leading threat was invasive pneumococcal disease, documented in 41 patients (68%) and causing 72 documented invasive infections (52.2%). P. aeruginosa and Staph. aureus documented invasive infections also occurred (16.7% and 16%, respectively, in 13 and 13 patients, respectively). Systemic signs of inflammation were usually weak or delayed. The first invasive infection occurred before the age of 2 years in 53 (88.3%) and in the neonatal period in 19 (32.7%) patients. Multiple or recurrent invasive infections were observed in most survivors (n = 36/50, 72%).Clinical outcome was poor, with 24 deaths, in 10 cases during the first invasive episode and in 16 cases of invasive pneumococcal disease. However, no death and invasive infectious disease were reported in patients after the age of 8 years and 14 years, respectively. Antibiotic prophylaxis (n = 34), antipneumococcal vaccination (n = 31), and/or IgG infusion (n = 19), when instituted, had a beneficial impact on patients until the teenage years, with no seemingly detectable impact thereafter.IRAK-4 and MyD88 deficiencies predispose patients to recurrent life-threatening bacterial diseases, such as invasive pneumococcal disease in particular, in infancy and early childhood, with weak signs of inflammation. Patients and families should be informed of the risk of developing life-threatening infections; empiric antibacterial treatment and immediate medical consultation are strongly recommended in cases of suspected infection or moderate fever. Prophylactic measures in childhood are beneficial, until spontaneous improvement occurs in adolescence.

Autoantibodies against IL-17A, IL-17F, and IL-22 in patients with chronic mucocutaneous candidiasis and autoimmune polyendocrine syndrome type I

Most patients with autoimmune polyendocrine syndrome type I (APS-I) display chronic mucocutaneous candidiasis (CMC). We hypothesized that this CMC might result from autoimmunity to interleukin (IL)-17 cytokines. We found high titers of autoantibodies (auto-Abs) against IL-17A, IL-17F, and/or IL-22 in the sera of all 33 patients tested, as detected by multiplex particle-based flow cytometry. The auto-Abs against IL-17A, IL-17F, and IL-22 were specific in the five patients tested, as shown by Western blotting. The auto-Abs against IL-17A were neutralizing in the only patient tested, as shown by bioassays of IL-17A activity. None of the 37 healthy controls and none of the 103 patients with other autoimmune disorders tested had such auto-Abs. None of the patients with APS-I had auto-Abs against cytokines previously shown to cause other well-defined clinical syndromes in other patients (IL-6, interferon [IFN]-gamma, or granulocyte/macrophage colony-stimulating factor) or against other cytokines (IL-1beta, IL-10, IL-12, IL-18, IL-21, IL-23, IL-26, IFN-beta, tumor necrosis factor [alpha], or transforming growth factor beta). These findings suggest that auto-Abs against IL-17A, IL-17F, and IL-22 may cause CMC in patients with APS-I.

Mutations in STAT3 and IL12RB1 impair the development of human IL-17-producing T cells

The cytokines controlling the development of human interleukin (IL) 17--producing T helper cells in vitro have been difficult to identify. We addressed the question of the development of human IL-17--producing T helper cells in vivo by quantifying the production and secretion of IL-17 by fresh T cells ex vivo, and by T cell blasts expanded in vitro from patients with particular genetic traits affecting transforming growth factor (TGF) beta, IL-1, IL-6, or IL-23 responses. Activating mutations in TGFB1, TGFBR1, and TGFBR2 (Camurati-Engelmann disease and Marfan-like syndromes) and loss-of-function mutations in IRAK4 and MYD88 (Mendelian predisposition to pyogenic bacterial infections) had no detectable impact. In contrast, dominant-negative mutations in STAT3 (autosomal-dominant hyperimmunoglobulin E syndrome) and, to a lesser extent, null mutations in IL12B and IL12RB1 (Mendelian susceptibility to mycobacterial diseases) impaired the development of IL-17--producing T cells. These data suggest that IL-12Rbeta1- and STAT-3--dependent signals play a key role in the differentiation and/or expansion of human IL-17-producing T cell populations in vivo.

Selective predisposition to bacterial infections in IRAK-4-deficient children: IRAK-4-dependent TLRs are otherwise redundant in protective immunity

Human interleukin (IL) 1 receptor–associated kinase 4 (IRAK-4) deficiency is a recently discovered primary immunodeficiency that impairs Toll/IL-1R immunity, except for the Toll-like receptor (TLR) 3– and TLR4–interferon (IFN)-a/b pathways. The clinical and immunological phenotype remains largely unknown. We diagnosed up to 28 patients with IRAK-4 deficiency, tested blood TLR responses for individual leukocyte subsets, and TLR responses for multiple cytokines. The patients' peripheral blood mononuclear cells (PBMCs) did not induce the 11 non-IFN cytokines tested upon activation with TLR agonists other than the nonspecific TLR3 agonist poly(I:C). The patients' individual cell subsets from both myeloid (granulocytes, monocytes, monocyte-derived dendritic cells [MDDCs], myeloid DCs [MDCs], and plasmacytoid DCs) and lymphoid (B, T, and NK cells) lineages did not respond to the TLR agonists that stimulated control cells, with the exception of residual responses to poly(I:C) and lipopolysaccharide in MDCs and MDDCs. Most patients (22 out of 28; 79%) suffered from invasive pneumococcal disease, which was often recurrent (13 out of 22; 59%). Other infections were rare, with the exception of severe staphylococcal disease (9 out of 28; 32%). Almost half of the patients died (12 out of 28; 43%). No death and no invasive infection occurred in patients older than 8 and 14 yr, respectively. The IRAK-4–dependent TLRs and IL-1Rs are therefore vital for childhood immunity to pyogenic bacteria, particularly Streptococcus pneumoniae. Conversely, IRAK-4–dependent human TLRs appear to play a redundant role in protective immunity to most infections, at most limited to childhood immunity to some pyogenic bacteria.

Primary immunodeficiency diseases: An update from the International Union of Immunological Societies Primary Immunodeficiency Diseases Classification Committee Meeting in Budapest, 2005

Although relatively rare, primary immunodeficiency diseases (PIDs) provide an excellent window into the functioning of the immune system. In the late 1960s, observations on these diseases, with their associated infections and genetics, bisected the immune system into humoral immunity and cell-mediated immunity. These diseases also represent a challenge in their diagnosis and treatment. Beginning in 1970, a unified nomenclature for the then-known PIDs was created by a committee convoked by the World Health Organization. Since then, and later under the aegis of the International Union of Immunological Societies, an international committee of experts has met every 2 to 3 years to update the classification of PIDs. During the past 15 years, the molecular basis of more than 120 PIDs has been elucidated. This update results from the latest meeting of this committee in Budapest, Hungary, in June 2005, which followed 2 1/2 days of scientific discussions. As a result of this work, new entities have been included, and the nomenclature of some PIDs (specifically of the various forms of class-switch recombination defects, previously known as hyper-IgM syndromes) has been changed.

Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses

Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.

Ephrin stimulation modulates T cell chemotaxis

Eph receptor tyrosine kinases and their ligands, the ephrins, are known to play an important role in regulating cell migration and targeting in neuronal and endothelial cells. Recently, it has been shown that lymphoid cells also express Eph receptors, raising the possibility that Eph receptors may similarly regulate lymphocyte migration. Chemotaxis in response to soluble chemokine factors is an essential facet of T cell biology. We demonstrate here that T cell chemotaxis in response to both the stromal cell-derived factor (SDF)-1alpha and macrophage inflammatory protein 3beta chemokines is modulated by costimulation with ephrins. Both ephrin-A and ephrin-B ligands were found to modify the chemotactic responses of a T cell line and primary T cells. Ephrin-A1, in particular, strongly inhibited chemotaxis. In accordance with the tyrosine kinase activity of EphA receptors, ephrin-A1 stimulation induced rapid intracellular tyrosine phosphorylation in T cells. Although strongly inhibiting chemotaxis, ephrin-A1 costimulus did not affect many of the signaling events downstream of the SDF-1alpha receptor CXCR4, including calcium flux and activation of MAPK. Rather, ephrin-A1 altered the balance of small G protein activity in T cells. Ephrin-A1 stimulation prevented SDF-1alpha-induced activation of cdc42, while simultaneously inducing rho activation. Ultimately, ephrin-A1 was found to inhibit chemokine-induced actin polymerization, thereby blocking migration. Ubiquitous ephrin expression in vivo creates enormous potential for T cells to encounter these ligands, suggesting that Eph receptors and ephrins may be important regulators of T cell migration.

Three new adenosine deaminase mutations that define a splicing enhancer and cause severe and partial phenotypes: implications for evolution of a CpG hotspot and expression of a transduced ADA cDNA

We report three novel adenosine deaminase (ADA) mutations with interesting implications. A Somali child with severe combined immunodeficiency disease (SCID) had reduced ADA mRNA in T cells and was homozygous for the nonsense mutation Q3X. Unexpectedly, her healthy father was a compound ADA heterozygote whose second allele carried a 'partial' mutation, R142Q, due to a G-->A transition of a CpG dinucleotide. A C-->T transition of the same CpG produced a nonsense mutation, R142X, in two homozygous Canadian Mennonite infants with SCID. The severe and healthy phenotypes associated with R142X and R142Q, the high frequency of 'partial' ADA mutations arising from CpGs in healthy individuals of African descent and the presence of CAA (glutamine) at codon 142 in murine ADA, suggest selection for replacement of this CpG hotspot by CpA during ADA evolution. R142X, located within a purine-rich segment at nt 62/116 of exon 5, caused skipping of the exon, possibly by disrupting a splicing enhancer. Absence of exon 5 in T cell ADA mRNA and low ADA activity in T cells and erythrocytes obtained at age 18-22 months from one of the Mennonite children, indicate limited expression of a normal ADA cDNA from retrovirally transduced CD34+ umbilical cord leukocytes infused shortly after birth in an attempt at stem cell gene therapy.

Localised pulmonary resection for bronchiectasis in hypogammaglobulinaemic patients

BACKGROUND

Bronchiectasis and pulmonary infections are common in patients with hypogammaglobulinaemia. Despite intravenous gammaglobulin treatment and appropriate antibiotics, a subgroup of patients remains with persistent localised pulmonary infection in segments where bronchiectasis had developed before appropriate treatment. As such localised pulmonary suppuration (segmental or lobar) may serve as a focus for progression of bronchiectasis, surgical resection of the involved segments may be considered. The outcome of pulmonary resection in four such patients is reported.

RESULTS

Surgery was well tolerated except for one postoperative empyema. Information on follow up is available from 3.5 to 5 years. All patients experienced considerable reduction of symptoms including cough, sputum production, antibiotic use, and hospital admissions.

CONCLUSIONS

Surgical resection of localised bronchiectatic segments should be considered in patients with hypogammaglobulinaemia with persistent localised suppuration and symptoms refractory to medical treatment.

Envelope glycoproteins of HIV-1 interfere with T-cell-dependent B cell differentiation: role of CD4-MHC class II interaction in the effector phase of T cell help

T-cell-dependent B cell differentiation involves two phases: an inductive phase of T cell activation followed by an effector phase, which involves stimulation of B cells by activated T cells. We have previously demonstrated that anti-CD3 mAb and antigen-induced T-cell-dependent B cell functions are inhibited by HIV-1 envelope glycoprotein, gp120, at the inductive phase of T-cell-dependent B cell response. In this study we have investigated whether gp120 also inhibits the effector phase of interactions involved in T-cell-dependent-B cell differentiation response. For these studies, CD4+ T cells were first activated with antigen or pokeweed mitogen, cultured with soluble HIV-gp120 or medium for 2 hr, and washed. Coculture of gp120-treated preactivated T cells with autologous B cells resulted in impairment of IgG secretion, but did not affect IgM secretion significantly. The IgG secretion was restored by the addition of PMA (activator of protein kinase C) or forskolin (activator of adenylate cyclase), but not by the addition of ionomycin (inducer of intracellular calcium) to the T plus B cell cultures. A similar pattern of Ig secretion (IgM, no IgG) was observed with B cells of a patient with bare lymphocyte syndrome, indicating a requirement for MHC class II molecule interaction with T cells. These studies suggest that the effector phase of T-B cell interactions are impaired by gp120, and that the mechanism involves a signal transducing event(s), which is dependent upon cyclic AMP and/or protein kinase C. Furthermore, these latter reactions occur subsequent to T-B cell contact-dependent interactions at the effector phase, which involve MHC class II molecules on B cells and CD4 molecules on T cells.

Constitutive expression and role in growth regulation of interleukin-1 and multiple cytokine receptors in a biphenotypic leukemic cell line

A cell line (B1) was established from the bone marrow of a patient with a relapse of acute leukemia characterized by a 4;11 chromosomal translocation and biphenotypic features of early B and myeloid lineages. Analysis of the growth requirements of this cell line showed density-dependent growth and secretion of an autostimulatory growth factor, suggesting an autocrine mechanism. Several lines of evidence implicate the participation of interleukin-1 (IL-1) in the autocrine growth regulation of B1 cells. These cells constitutively express the messenger RNA (mRNA) for IL-1 and IL-1 receptor and secrete IL-1; recombinant IL-1 stimulated the growth of colonies when cells were seeded at low density, and anti-IL-1 antibodies inhibited the growth of colonies with cells seeded at higher density. B1 cells do not express detectable levels of mRNA for any of the other cytokines tested, and other cytokines failed to support the growth of B1 cells at low density. In addition, B1 cells express multiple cytokine receptor genes, including the receptors for IL-6, IL-7, tumor necrosis factor and gamma-interferon. Addition of the respective cytokines to the B1 cells resulted in inhibition of the growth of leukemic cells in vitro. The multiplicity of growth-inhibitory cytokine receptors on this leukemic cell line might be due to its biphenotypic lineage and may suggest new therapeutic possibilities in controlling leukemic cell proliferation.

Modification in framework region I results in a decreased affinity of chimeric anti-TAG72 antibody

A mouse/human chimeric B72.3P-1-6 antibody was produced by construction of a novel expression vector mpSV2neo-EP2-V-Crl containing the same gene fragments as the expression vector mpSV2neo-EP1-V-Crl (Xiang J., Roder J. and Hozunni N., submitted to Molec. Immun., 1991) except the promoter (P2) fragment in which the translation start codon ATG is retained. The expression vector was transfected into a heavy chain loss mutant cell line, B72.3M1. The translation of the chimeric heavy chain may start at the exogenous start codon ATG within the P2 fragment, which is 27 base pairs upstream of the endogenous start codon ATG in B72.3 heavy chain V region cDNA fragment, leading to an alteration in leader sequence cleavage sites and the formation of chimeric heavy chain with an elongation in the FR1 region. Chimeric B72.3P-1-6 antibody retained binding specificity to TAG72 antigen, but showed an eight-fold decrease in binding affinity to TAG72 compared with chimeric B72.3-1-3 antibody. This suggests that residues in FRI contribute to the correct folding of the antibody binding region of the B72.3 antibody.

The diacylglycerol analogue, 1,2-sn-dioctanoylglycerol, induces an increase in cytosolic free Ca2+ and cytosolic acidification of T lymphocytes through a protein kinase C-independent process

In this paper, we demonstrate that low concentrations (0.5-2.5 microM) of 1,2-sn-dioctanoylglycerol (DiC8), a potent diacylglycerol used in many previous studies to probe the role of protein kinase C (PKC) in cell activation, cause cytosolic alkalinization of human, mouse and pig T lymphocytes through PKC-mediated activation of the Na+/H+ antiport. However, at higher concentrations (greater than or equal to 12.5 microM), the effect on cytosolic pH (pHi) is reversed, resulting in a marked cytosolic acidification, followed by a gradual return of pHi to baseline values. DiC8 also induces marked changes in cytosolic free calcium concentrations ([Ca2+]i), initially by releasing calcium from intracellular stores, followed by a net transmembrane influx of calcium. The DiC8-induced cytosolic acidification, the resultant return to baseline pH and the increase in [Ca2+]i are independent of activation of PKC. Unlike many other agents which increase [Ca2+]i, DiC8 does not induce phosphatidylinositol hydrolysis with the resultant production of inositol phosphates. Other compounds known to activate PKC, including the closely related diacylglycerol analogues, 1,2-sn-dihexanoylglycerol and 1,2-sn-didecanoylglycerol, phorbol esters and mezerein, did not induce changes in [Ca2+]i or cytosolic acidification in T lymphocytes. Thus the action of DiC8 on intact lymphocytes is different from that of phorbol esters and other diacylglycerols, and is specific to the length of the acyl chains. Because changes in [Ca2+]i are often associated with cell proliferation and cell differentiation, some effects of DiC8 on intact cells may be a consequence of changes in [Ca2+]i.

Physiologic activation of protein kinase C limits IL-2 secretion

Interaction of Ag, antibodies against the T cell receptor complex, or mitogenic lectins with T lymphocytes induces hydrolysis of membrane phospholipids leading to the production of diacylglycerol (DAG). DAG then activates the Ca2+- and phospholipid-dependent phosphotransferase, protein kinase C (PKC). Increases in DAG concentrations are transient as is the increase in PKC activity. Phorbol esters, which induce potent, prolonged activation of PKC, augment many T lymphocyte responses, including cell proliferation and secretion of the T cell growth factor IL-2. Therefore, it has been suggested that activation of PKC is a positive regulatory signal in T lymphocytes. We have determined the consequences of transient stimulation of PKC, and of depletion of PKC, on early cell activation signals and on production of IL-2 by the murine lymphoma line LBRM 331A5. When this cell line is depleted of PKC overnight incubation in high concentrations of phorbol esters, lectin-induced IL-2 secretion is augmented. Similarly, mitogen-induced changes in [Ca2+]i and phosphoinositide metabolism were augmented in these cells. In contrast, a short preactivation of PKC abrogated these early transmembrane signaling events. This suggested that normal physiologic activation of PKC may limit cell activation and decrease IL-2 production. We compared the effects of phorbol esters and mezerein, which produce prolonged activation of PKC, with those of diacylglycerol analogs, which induce transient activation of PKC. At concentrations that give similar levels of PKC activation, phorbol esters and mezerein, but not DAG analogs, increased IL-2 secretion. This suggests that prolonged, nonphysiologic activation of PKC is required to augment IL-2 secretion. Therefore, physiologic activation of PKC may not augment T cell activation but instead may function to decrease cell activation and limit IL-2 secretion.

Physiologic activation of protein kinase C limits IL-2 secretion

Interaction of Ag, antibodies against the T cell receptor complex, or mitogenic lectins with T lymphocytes induces hydrolysis of membrane phospholipids leading to the production of diacylglycerol (DAG). DAG then activates the Ca2+- and phospholipid-dependent phosphotransferase, protein kinase C (PKC). Increases in DAG concentrations are transient as is the increase in PKC activity. Phorbol esters, which induce potent, prolonged activation of PKC, augment many T lymphocyte responses, including cell proliferation and secretion of the T cell growth factor IL-2. Therefore, it has been suggested that activation of PKC is a positive regulatory signal in T lymphocytes. We have determined the consequences of transient stimulation of PKC, and of depletion of PKC, on early cell activation signals and on production of IL-2 by the murine lymphoma line LBRM 331A5. When this cell line is depleted of PKC overnight incubation in high concentrations of phorbol esters, lectin-induced IL-2 secretion is augmented. Similarly, mitogen-induced changes in [Ca2+]i and phosphoinositide metabolism were augmented in these cells. In contrast, a short preactivation of PKC abrogated these early transmembrane signaling events. This suggested that normal physiologic activation of PKC may limit cell activation and decrease IL-2 production. We compared the effects of phorbol esters and mezerein, which produce prolonged activation of PKC, with those of diacylglycerol analogs, which induce transient activation of PKC. At concentrations that give similar levels of PKC activation, phorbol esters and mezerein, but not DAG analogs, increased IL-2 secretion. This suggests that prolonged, nonphysiologic activation of PKC is required to augment IL-2 secretion. Therefore, physiologic activation of PKC may not augment T cell activation but instead may function to decrease cell activation and limit IL-2 secretion.

Corticosteroids-salicylate interaction in a case of juvenile rheumatoid arthritis

In an 11-year-old child with juvenile rheumatoid arthritis (JRA), the addition of prednisone caused a significant decrease in salicylate serum concentrations. A pharmacokinetic assessment suggested that these changes were not the result of altered compliance or impaired absorption of salicylate but rather an increase in salicylate clearance induced by the corticosteroid.

The regulatory role of interleukin 2-responsive T lymphocytes on human marrow granulopoiesis

The effect of recombinant interleukin 2 (IL2) on marrow CFU-C colony formation was evaluated to define the role for T lymphocytes in human marrow granulopoiesis. The colony-stimulating factor (CSA) used in our experiments was found to contain IL2. IL2 depletion from CSA resulted in a reduction in CFU-C colony proliferation. Addition of exogenous IL2 caused an increase in CFU-C colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody (MoAb) to the IL2 receptor. Moreover, anti-Tac in the absence of exogenous IL2 resulted in an overall decrease in colony numbers. Depletion of either adherent cells or T lymphocytes abolished the effect of IL2 and anti-Tac on colony growth. In the presence of IL2, re-addition of T lymphocytes to the T-depleted marrow or adherent cells to adherent cell-depleted marrow resulted in a significant increase in CFU-C colony numbers, whereas no significant effect was found when IL2-depleted CSA was used. Although T lymphocytes were not themselves essential for CFU-C colony growth, our studies indicate that IL2 and IL2-responsive T cells can regulate in vitro granulopoiesis.

The regulatory role of interleukin 2-responsive T lymphocytes on early and mature erythroid progenitor proliferation

To analyze the role of T lymphocytes in human erythropoiesis, we evaluated the effect of recombinant interleukin 2 (IL 2) on marrow CFU-E and BFU-E colony formation in vitro. IL 2 resulted in an increase in CFU-E and BFU-E colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody to the IL 2 receptor. Moreover, anti-Tac on its own resulted in an overall decrease in colony numbers. Depletion of marrow adherent cells did not alter the effect of either IL 2 or anti-Tac on colony growth. Following the removal of marrow T lymphocytes, CFU-E and BFU-E colony formation proceeded normally; however, the effects of IL 2 and anti-Tac were markedly diminished. Readdition of T lymphocytes to the cultures restored the IL 2 effect. Although T lymphocytes were not themselves essential for in vitro erythropoiesis, our studies suggest that IL 2 and IL 2-responsive T cells can regulate both early and mature stages of erythroid differentiation.

Sinus node dysfunction in a healthy pediatric population

ECG recordings of 624 healthy children (age range 6 to 12 years) from a rural population were analyzed for evidence of sinus node dysfunction. Twelve children were found to have the disorder and they underwent further assessment in order to establish any etiological factors or anatomical abnormalities. All the children were asymptomatic and physical examination was completely normal. Standard ECG taken during 24-h monitoring demonstrated that the most common finding, seen in 10 of 12 patients, was that of sinus arrest. Second-degree sinoatrial exit block, Mobitz type I, occurred in four children and Mobitz type II was seen in three. Two of the children were found to have holosystolic mitral valve prolapse, which was in the normal frequency range for a population of healthy children. After a 2-year follow-up and reassessment, there was no change in the symptomatology, the ECG tracings or the physical findings of any of the children.