A clinically important adverse drug reaction, heparin-induced thrombocytopenia (HIT), is induced by antibodies specific for complexes of the chemokine platelet factor 4 (PF4) and the polyanion heparin. Even heparin-naive patients can generate anti-PF4/heparin IgG as early as day 4 of heparin treatment, suggesting preimmunization by antigens mimicking PF4/heparin complexes. These antibodies probably result from bacterial infections, as (1) PF4 bound charge-dependently to various bacteria, (2) human heparin-induced anti-PF4/heparin antibodies cross-reacted with PF4-coated Staphylococcus aureus and Escherichia coli, and (3) mice developed anti-PF4/heparin antibodies during polymicrobial sepsis without heparin application. Thus, after binding to bacteria, the endogenous protein PF4 induces antibodies with specificity for PF4/polyanion complexes. These can target a large variety of PF4-coated bacteria and enhance bacterial phagocytosis in vitro. The same antigenic epitopes are expressed when pharmacologic heparin binds to platelets augmenting formation of PF4 complexes. Boosting of preformed B cells by PF4/ heparin complexes could explain the early occurrence of IgG antibodies in HIT. We also found a continuous, rather than dichotomous, distribution of anti-PF4/heparin IgM and IgG serum concentrations in a cross-sectional population study (n ‫؍‬ 4029), indicating frequent preimmunization to modified PF4. PF4 may have a role in bacterial defense, and HIT is probably a misdirected antibacterial host defense mechanism. (Blood. 2011;117(4): 1370-1378) IntroductionThe chemokine platelet factor 4 (PF4, CXCL4) is stored within platelet ␣-granules 1 and released during platelet activation. Although its biologic role is poorly understood, PF4 commands attention in clinical medicine because it binds charge-dependently to the anticoagulant heparin, one of the most frequently used anticoagulants in clinical medicine, thereby neutralizing heparin's anticoagulant effect, 2,3 but also forming highly antigenic multimolecular complexes. [4][5][6] The resulting antibody response 7 induces the most frequent immune-mediated adverse drug reaction involving human blood cells, heparin-induced thrombocytopenia (HIT). 8 The pathogenic antibodies bind to PF4/heparin complexes at the platelet surface, and the resulting immune complexes induce Fcreceptor-mediated platelet activation and enhanced thrombin generation. 8 In a subset of patients, this causes thrombocytopenia and triggers paradoxical thrombosis, which is aggravated by continuation of heparin treatment.The immune response of HIT has several atypical features. Even in patients who receive heparin for the first time, there is rapid induction (as early as 4 days) of anti-PF4/heparin antibodies of IgG isotype. Moreover, IgG antibodies are the predominant class of immunoglobulins formed. 9,10 We and others discovered that up to 50% of patients after cardiopulmonary bypass surgery and 20% to 30% of orthopedic surgery patients (many of whom have not been previously exposed to heparin) devel...

Cell migration is crucial for wound healing, immune defense, or formation of tumor metastases. In addition to the cytoskeleton, Ca2+ sensitive K+ channels (IK1) are also part of the cellular "migration machinery." We showed that Ca2+ sensitive K+ channels support the retraction of the rear part of migrating MDCK-F cells by inducing a localized shrinkage at this cell pole. So far the molecular nature and in particular the subcellular distribution of these channels in MDCK-F cells is unknown. We compared the effect of IK1 channel blockers and activators on the current of a cloned IK1 channel from MDCK-F cells (cIK1) and the migratory behavior of these cells. Using IK1 channels labeled with a HA-tag or the enhanced green fluorescent protein we studied the subcellular distribution of the canine (cIK1) and the human (hIK1) channel protein in different migrating cells. The functional impact of cIK1 channel activity at the front or rear part of MDCK-F cells was assessed with a local superfusion technique and a detailed morphometric analysis. We show that it is cIK1 whose activity is required for migration of MDCK-F cells. IK1 channels are found in the entire plasma membrane, but they are concentrated at the cell front. This is in part due to membrane ruffling at this cell pole. However, there appears to be only little cIK1 channel activity at the front of MDCK-F cells. In our view this apparent discrepancy can be explained by differential regulation of IK1 channels at the front and rear part of migrating cells.

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The use of a single non-absorbable polymeric clip is easy to use even for surgical trainees; it is safe and cost-effective. We suggest the use of a single clip for the closure of the appendicular stump as the standard procedure in laparoscopic appendectomy whenever possible.

This study analyses the effects of vagotomy on tumor growth and survival in a murine, pancreatic cancer model in wild-type and TNFα-knockout (−/−) mice.Throughout many operative procedures in the upper gastrointestinal tract the partial or complete transection of the vagus nerve or its local nerve fibers is unavoidable. Thereby its anti-inflammatory effects in residual tumor tissue may get lost. This effect may be mediated by tumor-associated macrophages (TAM) secreting TNFα.In an orthotopic murine pancreatic cancer model subdiaphragmatic vagotomy versus sham surgery was performed. The impact on tumor growth was monitored in wild type and TNFα −/− mice using MRI. TAMs as well as expression levels of TNFα were analyzed using immunohistochemistry. The role of TNFα on tumor growth and migration was examined in vitro. Vagotomised mice showed increased tumor growth with macroscopic features of invasive growth and had a shorter survival time. The loss of vagal modulation led to significantly increased TNFα levels in tumors and considerably elevated numbers of TAMs. In vitro TNFα significantly stimulated growth (p < 0.05) and migration (p < 0.05) of pancreatic cancer cells. TNFα −/− mice survived significantly longer after tumor implantation (p < 0.05), with vagotomy not affecting the prognosis of these animals (p > 0.05).Vagotomy can increase tumor growth and worsen survival in a murine pancreatic cancer model mediated through TAMs and TNFα. Hence, the suppression of TAMs and the modulation of TNFα dependent pathways could offer new perspectives in immunotherapies of pancreatic cancer patients especially with remaining vital tumor cells and lost vagal modulation.