Hidehiko Narazaki

Cutting Edge: Major CD8 T Cell Response to Live Bacillus Calmette-Guérin Is Mediated by CD1 Molecules

MHC class I-restricted CD8+ T cells are a crucial component of the host defense against mycobacterial infection in mice, but it has often proved very difficult to identify the CD8 T cell response in humans. Human group 1 CD1 molecules (CD1a, -b, -c) mediate MHC-independent presentation of mycobacteria-derived lipid and glycolipid Ags to CD8+ T cells, and their intracellular localization to the endocytic system may favor efficient monitoring of phagosome-resident mycobacteria. Here, we show that bacillus Calmette-Guérin (BCG)-immunized subjects contain a significant circulating pool of CD8+ T cells that recognize BCG-infected DCs in a CD1-dependent, but MHC-independent, manner. These CD1-restricted T cells efficiently detected live, rather than dead, BCG and produced IFN-γ, an important cytokine for protection against mycobacterial infection. These results emphasize that lipid-reactive CD8+ T cells may contribute to host defense against mycobacterial infection.

Perforin-dependent killing of tumor cells by Vγ1Vδ1-bearing T-cells

Abstract The T-cell subset expressing Vδ2 paired primarily with Vγ2 comprises a majority of γδ T-cells in human adult peripheral blood and expands significantly during a variety of infectious diseases. In contrast, the other subset of γδ T-cells that express Vδ1 is rare among circulating T-cells and its function is poorly understood. Here, we show that a Vγ1Vδ1 + T-cell line, 3-D, established from human peripheral blood by immortalization with Herpesvirus saimiri was able to specifically recognize tumor cells, such as K562 cells, and release cytotoxic granules containing perforin for target cell killing. Some tumor cells, including Daudi cells that are known to be susceptible to killing by Vδ2 + T-cells, were resistant to 3-D killing, implicating distinct pathways for tumor cell control by Vδ1 + and Vδ2 + T-cells. The 3-D T-cell receptor (TCR):CD3 complex reconstituted in TCR-deficient Jurkat cells was capable of transmitting signals, evidenced by activation of the interleukin 2 (IL-2) gene following ligation with anti-CD3 antibody, yet the TCR-reconstituted cells failed to produce IL-2 in response to the target cells. Thus, these results raise the possibility that some Vγ1Vδ1 + T-cells could potentially be stimulated and lyse tumor cells via ligation of TCR/CD3-unassociated molecules.

Melatonin overcomes resistance to clofarabine in two leukemic cell lines by increased expression of deoxycytidine kinase

Drug resistance remains a serious problem in leukemia therapy. Among newly developed nucleoside antimetabolites, clofarabine has broad cytotoxic activity showing therapeutic promise and is currently approved for relapsed acute lymphoblastic leukemia. To investigate the mechanisms responsible for clofarabine resistance, we established two clofarabine-resistant lymphoblastic leukemia cell lines from parental lines. To elucidate the mechanisms against clofarabine resistance in two newly established clofarabine-resistant cell lines, we measured the expression of export pumps multidrug resistance protein 1, multidrug resistance-associated protein 1, and ATP-binding cassette subfamily G member 2. There were no differences in the expression between clofarabine-sensitive and -resistant cell lines. Next, we determined expression of deoxycytidine kinase (dCK), which phosphorylates clofarabine to exert cytotoxicity, in clofarabine-sensitive and -resistant cells. Clofarabine-resistant cells showed significantly decreased expression of dCK RNA when compared with sensitive cells. To elucidate the mechanisms of decreased dCK expression in clofarabine-resistant cells, we analyzed the methylation status of CpG islands of the dCK promoter and found no differences in methylation status between clofarabine-sensitive and -resistant cells. Next, we measured the acetylation status of histone and found that total histone acetylation, and histone H3 and H4 acetylation on chromatin immunoprecipitation assay were significantly decreased in resistant cells. Melatonin is an indolamine that functions in the regulation of chronobiological rhythms to exert cytotoxic effects. We examined the effects of melatonin in clofarabine-resistant cells and found that melatonin treatment led to significantly increased cytotoxicity with clofarabine in resistant cells via increased acetylation. Melatonin may be a useful candidate for overcoming clofarabine resistance in two newly established clofarabine resistant leukemia cell lines.

Neglect-induced pseudo-thrombotic thrombocytopenic purpura due to vitamin B12 deficiency.

Although thrombotic thrombocytopenic purpura (TTP) is rare, early diagnosis and treatment are important for decreasing the mortality rate. Acquired vitamin B12 deficiency is frequently overlooked because of its rarity in developed countries, particularly in children and adolescents. The hematological changes in vitamin B12 deficiency present as megaloblastic anemia, increased lactate dehydrogenase, vasoconstriction, increased platelet aggregation, and abnormal activation of the coagulation followed by microangiopathy as well as neutropenia and thrombocytopenia. We report herein the case of a 15‐year‐old girl who had been neglected, which might have caused pseudo‐TTP through malnutrition, particularly vitamin B12 deficiency. When we encounter cases of TTP in children, clinicians must be aware of the possibility of malnutrition, particularly with vitamin B12 deficiency, even in developed countries, and investigate the cause of malnutrition including neglect.

Seronegative Antiphospholipid Syndrome with Anti-phosphatidylethanolamine Antibody in a Boy.

Antiphospholipid syndrome (APS) is an autoimmune disease caused by antiphospholipid antibodies. At our institution, APS is diagnosed on the basis of the Sapporo criteria, which consist of thrombosis and recurrent pregnancy-related complications and the following laboratory findings: the presence of lupus anticoagulant, anticardiolipin antibody, or anti-β2 glycoprotein 1 antibody. However, we sometimes treat patients we strongly suspect of having APS but who do not satisfy the laboratory criteria. To accommodate such suspected cases, a subtype of APS termed seronegative APS has been proposed. Here, we report on a man with chronic thromobocytopenic purpura since the age of 3 years and multiple cerebral infarctions since the age of 14 years who finally received a diagnosis of seronegative APS with positive antiphosphatidylethanolamine antibodies.

Genome‐wide DNA methylation profiling of CpG islands in a morpholino anthracycline derivative‐resistant leukemia cell line: p38α as a novel candidate for resistance

Effective leukemia treatment is seriously hampered by drug resistance. We previously showed that aberrant methylation of the topoisomerase IIα gene causes altered gene expression and acquired drug resistance in etoposide‐resistant leukemia cells. In this study, we analyzed the genome‐wide methylation status in resistant leukemia cells. We used MX2, which is a morpholino anthracycline derivative that functions as a topoisomerase IIα inhibitor. We established a human myelogenous leukemia cell line (K562/P) and a related cell line with resistance to MX2 (K562/MX2). Using these cell lines, we investigated the genome‐wide methylation status, compared expression profiles with a microarray, and analyzed the data using Gene Ontology and key node analysis. We demonstrate that the MX2‐resistant cell line was globally hypermethylated. Gene Ontology analysis identified genes involved in the immunological response and gene silencing that were responsible for methylation‐related altered gene expression in drug‐resistant cells. Key node analysis showed that p38α mitogen‐activated protein kinase was a novel enzyme involved in MX2‐related resistance. p38 kinase activity in resistant cells was increased compared to MX2‐sensitive parent cells. Blocking p38α activity using inhibitors and p38α knock down with small interfering RNA restored the sensitivity to MX2 in resistant cells with a decrease in p38 kinase activity as well as decreased expression of p38α mRNA and phosphorylated p38α protein. These findings may lead to a new strategy for treatment of drug‐resistant leukemia cells.

Pediatric immunoglobulin A complex secretory component deficiency

A female patient with normal birth and developmental history, who received immunizations according to the Japanese immunization schedule, developed atopic dermatitis at the age of 2 years. There was no history of immunodeficiency or autoimmune disease in her family. Subsequently, at approximately 4 years of age, she developed several infectious diseases, including Varicella zoster infection, impetigo, and acute otitis media. From the age of 5, she had frequent episodes of aphthous stomatitis and diarrhea. Additionally, she developed liver abscess that was surgically treated at the age of 5 years. At the age of 7, she was referred by a clinic to the present hospital because of fever, swelling of the right cervical lymph nodes, and persistent pain for 6 days. Laboratory data indicated a relatively normal responses against bacterial infection (Table 1). Due to chronic diarrhea and stomatitis, we suspected an immune system disorder. Initially, Behc et’s and Crohn’s disease were considered as differential diagnoses, but symptoms such as inflammation of the eyes, genital ulcers, and pathergy reaction, which are expected in Behcet’s, were not observed. Repeated sinopulmonary infections, gastrointestinal disorders, and an episode of liver abscess were suggestive of immunodeficiency. Initially, selective immunoglobulin A (IgA) deficiency was suspected because it is one of the most frequent primary immunodeficiency syndromes, and because secretory IgA plays an

Therapeutic Drug Monitoring Simulator for Antibiotic Dosage for Methicillin-Resistant Staphylococcus aureus Sepsis in a Patient with Primary Immunodeficiency on Peritoneal Dialysis

Bacterial infections often cause fatal systemic infections in patients with primary immunodeficiency. To prevent unfortunate results, the selection, dose, and dosage of antibiotics are extremely important. Here, we report a case of Wiskott-Aldrich syndrome in a patient undergoing peritoneal dialysis because of chronic renal failure in whom methicillin-resistant Staphylococcus aureus sepsis developed. Because of the primary disease and complications, teicoplanin was the only chosen anti-S. aureus drug to prevent side effects. We used parameter estimation and dosage adjustment from a therapeutic drug monitoring simulation software program to overcome the challenges with teicoplanin treatment.

Consideration of Glucocorticoids and Escherichia coli-derived L-asparaginase in the treatment of pediatric acute lymphoblastic leukemia

Glucocorticoids (GCs) are steroid hormones these are synthesized in the adrenal cortex. After binding to the nuclear glucocorticoid receptor (GR), activated GR complexes play a major role in immune system regulation by exerting a variety of effects such as inhibition of cyclooxygenase and inflammatory cytokines (IL-1, IL-2, IL-5, IL-6, INF-γ) synthesis, neutrophil induction, lymphocyte activation, etc. (1).