Wai S. Etches

Hepatosplenic T-cell lymphoma of αβ lineage in a 16-year-old boy presenting with hemolytic anemia and thrombocytopenia

The authors report an unusual case of peripheral T-cell lymphoma in a 16-year-old boy who presented initially with jaundice, splenomegaly, anemia, and thrombocytopenia. A lymphoma was found subsequently in the spleen, which was infiltrated extensively in the red pulp by medium-sized, blastic-appearing lymphoma cells. Immunologic characterization of these cells revealed positivity for CD3, CD5, CD45RO, CD56, and T-cell intracellular antigen (TIA), and negativity for CD2, CD3, CD4, CD8, CD57, CD34, and terminal deoxynucleotidyl transferase (TdT). Conventional cytogenetic studies revealed the presence of isochromosome 7q. On follow up, this patient deteriorated rapidly, with evidence of liver and bone marrow involvement. Although the overall clinical and pathologic features of this disease were characteristic of hepatosplenic gammadelta T-cell lymphoma, the T-cell receptor of this tumor showed an immunophenotype of alphabeta not gammadelta lineage. Using the Southern blot technique, the authors demonstrated monoclonal gene rearrangement of the T-cell receptor beta-chain. Thus, they confirmed the existence of hepatosplenic alphabeta T-cell lymphoma. In view of its overall similarity to hepatosplenic gammadelta T-cell lymphoma, this unusual entity probably represents a slight biologic variation of the same disease.

Heparin-induced thrombocytopenia: an improved method of detection based on lumi-aggregometry

Summary Heparin‐induced thrombocytopenia (HIT) is a recognized complication of heparin administration. Early detection of this syndrome is essential in the prevention of immune‐mediated thromboembolic sequelae. The 14C‐sero‐tonin release assay (SRA) has been used in reference laboratories to identify sera from patients on heparin therapy capable of inducing platelet dense granule release. In an attempt to improve existing methodologies, we employed luminographic detection of platelet‐dense granule ATP release as an endpoint of HIT antibody‐mediated platelet activation. Sera tested included 10 SRA confirmed positive and five SRA confirmed negative samples (to establish the assay), five samples from patients with thrombocytopenia not on heparin therapy and 34 patients suspected of HIT syndrome. All SRA confirmed positive sera (n= 19) were positive by the luminographic procedure. 24/26 SRA confirmed negative sera and five sera from thrombocytopenic patients not on heparin therapy were negative using luminography. Two of four sera yielding equivocal SRA results were found to be positive by the luminographic technique. The data suggest that the use of a lumi‐aggregometer in the coagulation laboratory to detect HIT antibody‐induced platelet activation is a reliable alternative to the SRA. The luminographic procedure is both rapid and sensitive, and does not require the use of biohazardous radio‐isotopes.

Flow cytometric detection of CD79a expression in T-cell acute lymphoblastic leukemias

We evaluated the lineage specificity of CD79a in acute leukemias using 3-color flow cytometry in 58 consecutive cases. A panel of cell-surface antigens, including myeloid-associated markers, B-cell-associated markers, and T-cell-associated markers, was used. All cases of acute myeloid leukemia were CD79a-, whereas all cases of B-lineage acute lymphoblastic leukemia (ALL) were CD79a+. Three of 8 cases of T-cell ALL showed variable CD79a expression, indicating the presence of a blast subset expressing a relatively high level of CD79a. We investigated the clinical and pathologic characteristics of these 3 cases. All 3 cases had L1 or L2 morphology and expressed surface CD3. None of the other B-cell-associated markers were positive, although 1 case expressed CD13 and CD33. Uncommon random karyotypic abnormalities were identified in all 3 cases. Molecular studies demonstrated monoclonal gene rearrangement of T-cell receptor gamma in 2 of 3 cases. All 3 patients were 18 years old or younger; 1 patient did not enter remission, and 1 had disease relapse in 8 months. Our findings provide further support for the existence of a subset of T-cell ALL coexpressing CD3 and CD79a. Further study of the clinical and biologic significance of this subset may be warranted.

Antiphospholipid antibody-dependent C5b-9 formation

The relationship between the presence of antiphospholipid antibodies (APA) and the production of the terminal membrane attack complex (MAC) of complement (C5b‐9) was studied. Serum samples from known high positive APA patients induced platelet activation and destruction which was inhibited by heat‐inactivation of the sera. The response was restored if the heat‐inactivated APA‐positive sera were supplemented with normal sera. Adsorption of the APA‐positive sera with phospholipid (PL)‐coated polystyrene beads inhibited platelet destruction. Addition of monoclonal antibody (mAb) to C5b‐9 (aE11) also inhibited platelet destruction, suggesting that the APA‐dependent platelet destruction might be complement‐mediated. Purified APA, in the presence of normal serum, induced C5b‐9 formation and binding to PL‐coated beads in a dose‐dependent manner as detected by flow cytometry. Prospective analysis of 200 serum samples for C5b‐9 production showed that all sera testing negative for the presence of APA also tested negative for C5b‐9 production. All sera with high levels of IgG binding to PL (GPL) showed evidence of C5b‐9 production. Sera with low or moderate GPL values showed varying levels of C5b‐9 production. These data suggest that complement may play a key role in APA‐dependent platelet activation, in vivo.

Phosphorylcholine-coated circuits improve preservation of platelet count and reduce expression of proinflammatory cytokines in CABG: a prospective randomized trial.

Abstract  Background: The interaction of blood with foreign artificial surfaces during cardiopulmonary bypass (CPB) has been recognized as a major stimulus in evoking a systemic inflammatory and metabolic response. Phosphorylcholine (PC) is a new‐generation coating material designed to ameliorate biocompatibility and thereby to reduce the detrimental interactions of CPB. We studied the effects of PC‐coated perfusion circuits on platelet function and the humoral and cellular response to CPB. Methods: Thirty patients undergoing coronary artery bypass grafting were randomized to PC‐coated (PC group, n = 15) and noncoated (control group, n = 15) circuit groups. Clinical data, total blood loss, and pre‐ and postoperative platelet counts were recorded and IL‐6 and TNF‐α, CD41a, CD42b, and CD62p were measured at induction of anesthesia, after the initiation of CPB and at termination of CPB. Results: There was a significantly improved preservation of platelet count following CPB in the PC group (p = 0.028), which was sustained over a period of 72 hours. The use of PC‐coated circuits further resulted in a significant attenuation of TNF‐α and IL‐6 expression (p < 0.05 and p < 0.01); however, we were unable to detect any differences in clinical outcomes. Conclusions: Despite similar clinical outcome, the obvious reduction of cytokine expression and improved preservation of platelet count suggest superior biocompatibility of PC‐coated circuits.

Caterpillar-induced bleeding syndrome in a returning traveller

The case: A 22-year-old woman who was previously healthy presented with a 4-day history of expanding ecchymoses. She had no other bleeding manifestations and denied any constitutional symptoms, myalgias, arthralgias or rashes. Her medical history was unremarkable. She was not taking any medication,

Platelet activation by a novel solid‐phase agonist: effects of VWF immobilized on polystyrene beads

The interaction between platelets stirred in suspension and VWF immobilized on polystyrene beads was studied. Platelets aggregated and released ATP in response to stirring with VWF beads. Closer examination of the interaction using transmission electron microscopy revealed that the platelets did not simply aggregate with one another but initially adhered to the beads and spread. Platelets in suspension then bound to the bead‐adherent platelets forming layers of platelets associated with each bead. The VWF bead‐induced platelet activation was com‐pletely inhibited by addition of monoclonal antibody (mAb) to GPIb or GPIIb/IIIa. In addition, the activation response was inhibited in the presence of aspirin, indomethacin or the thromboxane receptor antagonist BM13.177, demonstrat‐ing a dependence on an intact cyclo‐oxygenase pathway.  Platelet function studies were carried out on 30 patients with a history of mild bleeding using conventional optical aggregation and VWF bead‐induced platelet activation. 12 patients were abnormal by conventional optical aggregometry, whereas 27 patients showed depressed ATP release in response to VWF beads. The results suggest that easily‐bruised patients may have a platelet function defect rather than a vascular‐based abnormality and that VWF bead‐induced platelet activation is a more sensitive test for detecting platelet dysfunction.