Kondo H

Binding of Cobalamin Analogs to Intrinsic Factor-Cobalamin Receptor and Its Prevention by R Binder

Abstract It is now known that nonphysiological cobalamin analogs exist in the gastrointestinal tract, but their metabolic behavior is unclear. In this study, [57Co]cobinamide was used to study its affinity to hog intrinsic factor-cobalamin (IF-Cbl) receptor which has no species specificity against human IF-Cbl receptor, and its relation to human saliva R binder. Cobinamide was prepared from [57Co]cyanocobalamin and separated by paper chromatography. Human IF-Cbl complex was bound to IF-Cbl receptor but free cyanocobalamin was not. Although R binder-cobinamide was not bound to the IF-Cbl receptor, free cobinamide was bound to the IF-Cbl receptor to a significant extent (about one-half of IF-cyanocobalamin binding to the IF-Cbl receptor). We then investigated the binding of cobinamide to R binder and trypsin-treated R binder. Association constant of cobinamide binding to the IF-Cbl receptor was 1.0 × 109 M -1 which was much lower than that of cobinamide binding to trypsin-treated R binder and to untreated R binder. Further study indicated that cobinamide binding to the IF-Cbl receptor was blocked by the addition of R binder and also by trypsin-treated R binder. We conclude that one of the roles of R binder is to prevent binding of free cobalamin analogs to the IF-Cbl receptor in the gut.

Effects of intravenous immunoglobulin in a patient with intermittent thrombotic thrombocytopenic purpura

We describe a patient with a 9‐year history of thrombotic thrombocytopenic purpura (TTP) who exhibited four relapses. Intravenous immunoglobulin (IVIg) was effective for these four episodes. The patient was well and the laboratory findings were within normal ranges between each episode, although unusually large von Willebrand factor multimers were observed during remission. Our results suggest the usefulness of IVIg at the time of relapse in the treatment of patients with TTP who have multiple relapses over a long period.

Effects of simultaneous rhG-CSF and methylprednisolone "pulse" therapy on hepatitis A virus-associated haemophagocytic syndrome.

To the Editor: We describe a patient with hepatitis A (HA)-virus associated haemophagocytic syndrome successfully treated with simultaneous rhG-CSF and methylprednisolone. A 49-year-old woman was admitted because of fever and icterus. Liver dysfunction was evident with elevated serum bilirubin and various enzymes (Fig. la). Serology for hepatitis A virus (IgM) was positive; for hepatitis B and C, CMV, herpes zoster, herpes simplex, adenovirus, and human immunodeficiency virus all negative; and for EBV (IgG) positive, EBV (IgM) negative. Acute hepatitis due to HA virus was diagnosed, although marked splenomegaly was unexampled. She was given supportive treatment followed by amelioration of liver function tests, although pyrexia continued and skin rashes appeared over her trunk with progression of pancytopenia (Fig. lb). A blood test on March 30 revealed that the haemoglobin concentration was 5.9 g/dl, leukocyte count 0.5 x 109/1, comprised of 0% neutrophils, and platelet count 32 x 109/l. Bone marrow examination was compatible with VAHS, showing hypopcellularity of haematopoietic components with hyperplasia of reticulum cells (reticulum cells, 50% of nucleated cell) exhibiting haemophagocytosis (Fig. 2a, 2b). Further investigations showed that both serum ferritin and sIL2R level were high (Fig. la). VAHS was diagnosed and rhG-CSF and methylprednisolone “pulse” therapy was initiated. Pancytopenia was ameliorated shortly after initiation of the treatment. Bone marrow examination after discontinuation of the treatment showed normal maturation of haematopoietic components and disappearance of reticulum cells. Since the original description of VAHS (l), laboratory studies have shown evidence of acute viral infection in most patients who have been thoroughly evaluated for various viral disease (2). To our knowledge, there has been only one reported case of VAHS due to hepatitis A virus (3) in which the patient was an immunocompromised host. The patient presented in the present report represents the first case of hepatitis A-associated VAH S in an immunocompetent subject. This patient showed good evidence of hepatitis A infection with no positive serology for any other acute viral or bacterial infections. Unusually for hepatitis A, her spleen was markedly enlarged, and this was presumably due to infiltration with histiocytes. It has been suggested (4) that there is an alteration of T-cell function in VAHS, with uncontrolled T cells producing large amounts of cytokines. Secondary activation of macrophages may then result in haemophagocytosis followed by hyperferritinaemia. Good correlations between serum levels of ferritin and of sIL2R and the clinical course were observed in our patient (Fig. la). Although IFN-)I, TNF and IL-lP were not increased, that may be explained by the mild disease state. Aplastic anaemia is a usual cause of pancytopenia after viral hepatitis. There is increasing evidence that a variety of infectious agents alter haematopoiesis through effects on the microenvironment (5). One of the major causes of haematopoietic aplasia after hepatitis virus infection may be due not to the stem cell defect, but to the microenvironment disturbance. The present report substantiates that VAHS is an important cause of the myelosuppressive state after viral hepatitis and suggests that precise histological evaluations are needed. Management of VAHS has usually been anticipatory with supportive measures. However, the considerable reported mortality rate ( 6 ) and severe neutropenic conditions in our patient prompted us to use methylprednisolone “pulse” with rhG-CSF regimes. The dramatic haematopoietic recovery with this regime might be due to up-modulation of IL-1R expression on haematopoietic cells by synergetic ac-

EFFECT OF INTRAVENOUS GAMMAGLOBULIN INFUSION ON RECURRENT EPISODES OF THROMBOTIC THROMBOCYTOPENIC PURPURA (TTP)

To the editor: We describe a patient with recurrent thrombotic thrombocytopenic purpura (TTP) successfully treated with intravenous gammaglobulin infusion. A 60-year-old man was admitted because of fever, anemia, hemorrhagic manifestations and neurological abnormalities in May, 1990 (Fig. la). A blood analysis revealed that hemoglobin was 6.8 g/dl, reticulocyte 17.3%, white cell count 7.1 x 10y/l, and platelet count 8 x 109/l. Peripheral blood smear demonstrated fragmentation of red cells with a few erythroblasts. Bone marrow examination disclosed marked erythroid hyperplasia. Hemostatic data were within normal ranges except that for bleeding time. The serum birilubin was 1.57 mg/dl and LDH level 1437U/1. Haptoglobin was below 10 mg/dl. Urinalysis disclosed proteinuria, microhematuria and trace amounts of granular and hyaline casts. TTP was diagnosed on the basis of these symptoms and the results of these various laboratory examinations. He was initially treated with glucocorticoid and various anti-platelet agents with fresh frozen plasma and platelet infusion, but showed no improvement of hematological parameters or symptoms. The clinical features and laboratory values dramatically improved after the administration of gammaglobulin (20 g/day) for 3 d (Fig. la, June 23, 24, 25). Complete remission ensued without further gammaglobulin infusion or any other treatment. The patient remained clinically and hematologically normal for 1 yr after this treatment. In August, 1991, he complained of cutaneous hemorrhagic tendency. Blood analysis revealed anemia, thrombocytopenia and reticulocytosis. A diagnosis of recurrent of TTP was made; clinical course is shown in Fig. lb. He was treated with platelet and fresh frozen plasma infusion and showed improvement of platelet count (Fig. lb, Aug 2-8). However, the anemia progressed and the platelet count decreased again (Aug 8-14). After infusion of gammaglobulin (3 g/d) for 3 d (Aug 16-18), the platelet count was elevated in the absence of platelet infusion, and the reticulocyte count decreased, followed by recovery from the anemia. After the 2nd infusion of gammaglobulin at the same dose (Sept 4-6), the platelet count increased in the absence of either platelet or fresh frozen plasma infusion. He has remained asymptomatic and hematological data have been within normal range without any drugs since September 26 (Fig. lb). Since TTP was first described (l), numerous types of therapy have been advocated for this disease. Given the unresolved questions as to the cause and pathogenesis of this disease, it is not surprising that highly variable results have been obtained with each of the numerous forms of therapy which have been devised to treat this syndrome. Although plasma exchange, with replacement by fresh frozen plasma, has recently become the mainstay in the therapeutic management of this disease, this method is expensive and hazardous, and some patients do not respond to this treatment. While other types of therapy, such as antiplatelet drugs, vincrisitine, steroid, and splenectomy, are also used, the effects of these are controversial. Among them, intravenous gammaglobulin has been shown to be effective in patients with this disease in a few studies (2). The plasma of some patients with TTP presumably contains a platelet-aggregating factor of unknown origin, whereas normal plasma possesses IgG which is thought to have the capacity to neutralize the factor (3). Several clinical trials of intravenous gammaglobulin infusion for patients with this disease have been performed under this hypothesis, and, in five of the six studies of which we are aware, the effectiveness of this therapy was demonstrated (4). Chronic and relapsing variants of TTP, though reported, are not common (5) . The findings in this case reaffirm that TTP in a patient in remission in the absence of therapy for over 1 yr may recur, and affirm the usefulness of gammaglobulin in treatment of patients who relapse. These data suggest that this modality should be considered in the treatment of refractory cases at both the initial and recurrent phases.

High-dose intravenous immune globulin and the response to splenectomy monitoring with platelet-associated IgG in patients with idiopathic thrombocytopenic purpura.

To the Editor: We examined whether the response to intravenous immune globulin (IVIg) can predict the response to splenectomy and whether measurement of plateletassociated IgG (PAIgG) can estimate the clinical outcome of patients with idiopathic thrombocytopenic purpura (ITP). The clinical courses of the 3 patients are shown in Fig. la,b,c. The PAIgG levels, which were determined by a competitive microenzyme-linked immunoassay (ELISA) as described before (1) (normal range: 9.0-25.0 ng/107 cells), of all the patients markedly increased before the treatment of IVIgG and the splenectomy and they did not decrease to the normal range after the treatment with prednisolone, even after the platelet counts had increased to normal levels.

Antithymocyte Globulin in the Treatment of D-Penicillamine—Induced Aplastic Anemia

A patient who received antithymocyte globulin therapy for aplastic anemia due to D-penicillamine therapy is described. Bone marrow recovery and peripheral blood recovery were complete 1 month and 3 months, respectively, after treatment, and blood transfusion or other therapies were not necessary in a follow-up period of more than 2 years. Use of antithymocyte globulin may be the optimal treatment of D-penicillamine—induced aplastic anemia.

Human Monoclonal Antibody Detects a Cell Surface Antigen Expressed on Hematopoietic Malignant Cells of Lymphoid Lineage

An antigen with a molecular weight of 150 kilodaltons expressed on certain leukemia and lymphoma cells was recognized by a human monoclonal antibody (3H12), which had been established by the fusion of lymphocytes from a small cell lung cancer patient with a mouse myeloma cell line (P3U1). Peripheral blood mononuclear cells from 3 out of 4 cases with lytnphoid crisis of chronic myelogenous leukemia (CML) were positively stained by 3H12, while cells from 5 cases with myeloid crisis of CML did not react to this antibody. The antibody did not show any reactivity to cells from the chronic phase of CML, other types of leukemias or normal hematopoietic cells. We further examined 29 cell lines of hematopoietic origin and found that 2 undifferentiated cells (BV‐173 and K‐562) reacted to the 3H12 antibody. In addition, we found that 3 out of 6 Burkitt lymphoma cells (DAUDI, RAJI and HR1K) reacted to 3H12. Taken together, these results suggest that the antigen recognized by 3H12 is a differentiation‐associated antigen expressed on immature lymphoid cells, and could potentially be a reliable cell lineage marker.