Drug-dependent clearance of human platelets in the NOD/scid mouse by antibodies from patients with drug-induced immune thrombocytopenia

Abstract

Drug-induced immune thrombocytopenia (DITP) is a relatively common and sometimes life-threatening condition caused by antibodies that bind avidly to platelets only when drug is present. How drugdependent antibodies (DDAbs) are induced and how drugs promote their interaction with platelets are poorly understood, and methods for detecting DDAbs are suboptimal. A small animal model of DITP could provide a new tool for addressing these and other questions concerning pathogenesis and diagnosis. We examined whether the nonobese diabetic/ severe combined immunodeficient (NOD/ scid) mouse, which lacks xenoantibodies and therefore allows infused human platelets to circulate, can be used to study drug-dependent clearance of platelets by DDAbs in vivo. In this report, we show that the NOD/scid model is suitable for this purpose and describe studies to optimize its sensitivity for drug-dependent human antibody detection. We further show that the mouse can produce metabolites of acetaminophen and naproxen for which certain drug-dependent antibodies are specific in quantities sufficient to enable these antibodies to cause platelet destruction. The findings indicate that the NOD/ scid mouse can provide a unique tool for studying DITP pathogenesis and may be particularly valuable for identifying metabolite-specific antibodies capable of causing immune thrombocytopenia or hemolytic anemia. (Blood. 2010;116(16): 3033-3038) IntroductionDrug-induced immune thrombocytopenia (DITP) can be triggered by various medications through several distinct mechanisms. 1,2 In a comprehensive survey of DITP cases reported since 1998, George and coworkers identified 17 drugs that were considered to be "probable" causes of DITP and 51 thought to be "definite" causes on the basis of having met, respectively, 3 or 4 well-defined clinical criteria. 3,4 This analysis has helped greatly to define which drugs are capable of causing DITP but does not provide proof in an individual patient that a particular drug was responsible. Evidence supporting a cause-and-effect relationship between drug exposure and thrombocytopenia can be obtained by identifying a drugdependent antibody (DDAb) that reacts with platelets only when the implicated drug is present. 1,2,5 However, relatively few laboratories are experienced in DDAb detection, and it is not rare for antibody testing to be negative in a patient with a clinical history strongly suggestive of DITP. 1,2 Moreover, there is not uniform agreement as to whether detection of a DDAb provides conclusive evidence that the antibody caused platelet destruction. Partly for these reasons, identification of a DDAb is not included among the George criteria. The most stringent of these criteria calls for thrombocytopenia to recur when a patient is exposed a second time to the implicated drug. 3 While a rechallenge can provide convincing evidence that thrombocytopenia was drug-induced, it is often impractical and can be difficult to justify for reasons of patient safety.A surrogate small animal model for direct demonstration...

Mechanism of quinine-dependent monoclonal antibody binding to platelet glycoprotein IIb/IIIa

“…by guest www.bloodjournal.org From with platelets in vitro 27 and in their ability to promote drug-dependent destruction of human platelets in a mouse model. 28 Even differential reactions of the two mAbs with platelets in the presence of the quinine structural analogs cinchonidine, cinchonine, and quinidine, mirror the behavior of antibodies from patients with quinineassociated DITP, 27 the major difference being that the mAbs recognize their targets at lower drug concentrations than their human counterparts. Parallel behavior of the human and murine antibodies in vitro and in vivo favors the likelihood that findings made with the mAbs are relevant to mechanisms responsible for DITP in patients sensitive to quinine.…”

“…28 mAb 314.1 labeled with Alexa Fluor 488 or its Fab fragments labeled with Alexa Fluor 633 were added to 2.4 3 10 5 platelets in the presence or absence of quinine (0.1 mM) in a final volume of 0.1 mL to produce indicated final concentrations. After 90 minutes at room temperature and without any further dilution, plateletbound IgG was analyzed by flow cytometry (LSRII; Becton Dickinson, Franklin Lakes, NJ).…”

“…We recently produced several quinine-dependent murine monoclonal antibodies (mAbs) that recognize epitopes located at the amino (N) terminus of the GPIIb b propeller domain only in the presence of quinine, and closely resemble antibodies that cause thrombocytopenia in patients taking quinine in their drug-dependent reactions with platelets in vitro 27 and their ability to cause destruction of human platelets in nonobese diabetic/severe combine immunodeficiency (NOD/SCID) mice given quinine. 28 Here, we describe studies of the mechanism by which quinine enables them to react with their target integrin.…”

CD8+ T cells mediate antibody-independent platelet clearance in mice

“…2,3 While clearance can occur through nonimmune-related mechanisms, 4 many studies demonstrate the importance of immune-mediated clearance. 2,3,[5][6][7][8] Historically, immune-mediated platelet clearance, termed refractoriness, was attributed solely to anti-platelet alloantibodies predominately targeted to major histocompatibility complex (MHC) antigens.…”

Effects of Ascaris suum Extract and Sulfamethoxazole on Allergic Airway Inflammation

“…SMX, kind of sulfonamides that induced DRESS syndrome is associated with drug-induced immune thrombocytopenia in murine model (Bougie et al, 2010). SMX and its metabolites in a mouse model have been shown to allow quantitative and qualitative characterization of immune response provoked by different classes of chemical allergen.…”