Comparative analysis of the pathological events involved in immune and non-immune TRALI models.

BACKGROUND AND OBJECTIVES: Transfusion-related acute lung injury (TRALI) is characterized by leukocyte transmigration and alveolar capillary leakage shortly after transfusion. TRALI pathogenesis has not been fully elucidated. In some cases, the infusion of alloantibodies (immune model), whereas in others the combination of neutrophil priming by proinflammatory molecules with the subsequent infusion of biological response modifiers (BRMs) in the hemocomponent (non-immune model) have been implicated. Our aim was to compare the pathological events involved in TRALI induced by antibodies or BRMs using murine models. MATERIALS AND METHODS: In the immune model, human HNA-2(+) neutrophils were incubated in vitro with a monoclonal antibody (anti-CD177, clone 7D8) directed against the HNA-2 antigen and injected i.v. in NOD/SCID mice. In the non-immune model, BALB/c mice were treated with low doses of lipopolysaccharide (LPS) followed by platelet-activating factor (PAF) infusion 2 h later. Forty minutes after PAF administration, or 6 h after neutrophil injection, lungs were isolated and histological analysis, determination of a variety of cytokines and chemokines including keratinocyte-derived chemokine (KC), MIP-2, the interleukins IL-1ß, IL-6, IL-8 as well as TNFα, cell influx and alveolar capillary leakage were performed. RESULTS: In both models, characteristic histological findings of TRALI and an increase in KC and MIP-2 levels were detected. In contrast to the immune model, in the non-immune model, there was a dramatic increase in IL-1ß and TNFα. However, capillary leakage was only detected if PAF was administrated. CONCLUSIONS: Regardless of the triggering event(s), KC, MIP-2 and integrins participate in TRALI pathogenesis, whereas PAF is essential for capillary leakage when two events are involved.

Expression of recombinant human antibody fragments capable of inhibiting the phospholipase and myotoxic activities of Bothrops jararacussu venom.

Phospholipases A(2) are components of Bothrops venoms responsible for disruption of cell membrane integrity via hydrolysis of its phospholipids. This study used a large nonimmune human scFv library named Griffin.1 (MRC, Cambridge, UK) for selection of recombinant antibodies against antigens present in Bothrops jararacussu venom and identification of specific antibodies able to inhibit phospholipase activity. Four clones were identified as capable of inhibiting this activity in vitro. These clones were able to reduce in vivo the myotoxic activity of BthTX-I and BthTX-II PLA(2), but had no effect on the in vitro anticoagulant activity of BthTX-II. This work shows the potential of using recombinant scFv libraries in the search for antibodies that neutralize relevant venom components.