Dominique Latinne

Bedside transfusion errors : a prospective survey by the Belgium SAnGUIS group

The true incidence of bedside transfusion errors, i.e. those happening when blood products have left the blood bank, is underestimated because published figures rely on reporting of clinically relevant events or on indirect methods. The SAnGUIS project assessing blood practice in a prospective and randomized fashion for 6 elective surgical procedures gave the opportunity to trace all transfused units and to identify steps at risk during blood delivery in surgery. We considered transfusion of a wrong unit as a major error and poor execution or documentation as a recording error.

Characterization of baboon anti-porcine IgG antibodies during acute vascular rejection of porcine kidney xenograft

In the pig‐to‐baboon model, the removal of anti‐porcine natural antibodies abrogates hyperacute vascular rejection (HAVR), but the xenograft then undergoes an acute vascular rejection (AVR) concomitantly to the appearance of newly formed anti‐porcine antibodies. The use of anti‐IgM monoclonal antibody (mAb) in baboons allowed to avoid HAVR of pig‐to‐baboon renal xenografts, but, at post‐operative day 6, AVR occurred because of a rapid return of anti‐porcine antibodies. The aim of this work was to characterize the anti‐porcine antibodies during AVR. Sera from anti‐IgM‐treated animals were assessed prior to the graft and at the time of AVR by enzyme linked immunosorbent assay (ELISA) to determine anti‐porcine antibodies concentration as well as the IgG subtypes. The same sera were tested on confluent cultures of porcine aortic endothelial cells (PAECs) to assess (i) the cytolytic complement‐dependent activity and (ii) the E‐selectin expression. The K affinity of anti‐Gal IgG antibodies was measured by ELISA. Anti‐porcine (Gal and non‐Gal) IgG antibodies were tested on PAECs by flow cytometry to discriminate the presence of Gal epitopes from the recognition of other porcine epitopes. We found that both anti‐porcine IgM and IgG antibodies presented a significantly increased cytolytic activity and E‐selectin expression on PAECs during AVR. These characteristics are related to an important increase of the antibody (Ab) titer (especially anti‐galactosyl) and a switch to anti‐galactosyl IgG1 subclass production, whereas the K affinity remained unchanged. The deleterious effects of both IgM and IgG antibodies observed during AVR showed the crucial need for treatment controlling the cells producing anti‐porcine antibodies.

In vitro and in vivo investigation of a novel monoclonal antibody to plasma cells (W5 mAb)

Abstract:u2002 Natural antibodies (Abs), predominately anti‐Galα1–3Gal (Gal) Abs, in non‐human primates and human beings present a major hurdle to successful pig‐to‐primate xenotransplantation. Attempts to inhibit anti‐Gal Ab production in naïve baboons using non‐specific immunosuppressive or B cell‐specific reagents have failed. A new rat monoclonal antibody (W5 mAb) has been generated, which binds to all B cells, including memory cells, and to the majority of plasma cells, but not to T cells. It has been tested in vitro and in vivo. By immunoprecipitation, W5 mAb bound a human leukocyte antigen class II (HLA‐DR) determinant. Sorting splenic or bone marrow W5+ cells resulted in a highly enriched anti‐Gal Ab and total immunoglobulin (Ig)‐secretory population. In vivo studies in baboons demonstrated that W5 mAb was safe but, despite the concomitant administration of an anti‐CD154 mAb to inhibit sensitization, anti‐rat Abs were detected within 10u2003days and inhibited the effect of the W5 mAb. High levels of W5 mAb were able to completely deplete B cells in the blood, but not in lymphoid tissues. Enzyme‐linked spot‐forming assay (ELISPOT) demonstrated that only 50 to 60% of secreting cells (SC) were depleted in the bone marrow. No reduction in the serum levels of anti‐Gal Ab was observed. W5 mAb did not cause complete inhibition of anti‐Gal Ab production, probably as a result of its inability to completely deplete B and plasma cells from all lymphoid compartments.

Human and non-human primate anti-galactosyl response after injection of rat monoclonal antibody bearing galactosyl epitopes.

Abstract: In the case of clinical use of pig‐to‐human xenografting, any exogenous source of α‐galactosyl epitopes will elicit an anti‐galactosyl immune response, which could be deleterious for the xenograft. The presence of Galα(1–3)Gal residues was thus examined by western blotting on various rat monoclonal antibodies (mAb), which are used in clinical trials. In parallel, the anti‐galactosyl humoral response was assessed in the serum of kidney allograft recipients and experimental baboons, which received these mAbs. Galactosyl residues were evidenced on all rat monoclonal antibody tested. The anti‐galactosyl response was weak in kidney allograft recipients receiving a basic immunosuppression (Cyclosporine, Azathioprine, Prednisolone) and iterative injections of rat mAbs. In contrast, untreated or immunosuppressed baboons that received rat mAbs developed a major anti‐galactosyl humoral response. These results suggest that anti‐galactosyl sensitization produced by therapeutic agents will have to be considered in the case of clinical xenotransplantation.

HLA-Antigens in Multiple Sclerosis Patients in the Benelux

The association of multiple sclerosis (MS) with HLA-A3, B7 and DR2 is well established in most northern European populations suggesting the existence of an MS susceptibility locus closely linked to HLA. The demonstration of a negative association has been more problematic due to compensatory decreases in frequencies of antigens other than DR2 and antigens in linkage disequilibrium. Attempts have also been made to correlate HLA antigens and clinical characteristics including type of disease course and rate of progression (Madigand et al. 1982, Meyer-Rienecker et al. 1982).