Activation of the lectin pathway of complement by cardiopulmonary bypass contributes to the development of systemic inflammatory response syndrome after paediatric cardiac surgery

The systemic inflammatory response is a challenge in the management of paediatric patients undergoing cardiac surgery. Although multi-factorial, a contribution by the lectin pathway of complement activation has been postulated. We therefore investigated the changes in serum levels of mannose binding lectin (MBL) and activities of MBL-MBL-associated serine protease (MASP)-1 and MBL-MASP-2 complexes immediately before and during surgery, throughout the first postoperative day and at discharge from the hospital. These changes were analysed in relation to postoperative complications. Blood samples were obtained from 185 children with congenital heart disease undergoing surgical correction with the use of cardiopulmonary bypass: preoperatively (MBL-1), 15 min after initiation of cardiopulmonary bypass (CPB) (MBL-E), 30 min (MBL-2), 4 h (MBL-3), 12 h (MBL-4) and 24 h (MBL-5) post-CPB and at discharge from hospital (MBL-K). Alterations in serum MBL levels were calculated as a ratio of its serum level at subsequent time-points (MBL-2, -3, -4, -5) to the preoperative (MBL-1) value. Decreases in MBL and MBL-MASP complexes were observed in all samples, correlating with a decrease in C4 and increase in C4a, confirming activation of the lectin pathway. Changes in MBL levels between children with an uncomplicated postoperative course and those suffering from infection or low cardiac output syndrome did not differ significantly, but significant differences were observed between the SIRS and non-SIRS groups. Paediatric cardiac surgery with the use of cardiopulmonary bypass activates the complement system via the lectin pathway and the latter contributes to the development of the post-bypass systemic inflammatory response.

Assessment for possible healthcare-associated transmission of a new variant influenza virus--Pennsylvania, August 2011

In August 2011, one of the earliest cases of influenza A(H3N2) variant [A(H3N2)v] virus infection was hospitalized with severe illness. To investigate the potential for healthcare-associated transmission of influenza A(H3N2)v, we evaluated both healthcare providers and patient contacts of the case. We found that healthcare-associated transmission was unlikely.

NK cells and CD1d-restricted NKT cells respond in different ways with divergent kinetics to IL-2 treatment in primary HIV-1 infection

Cytokine immunotherapy is being evaluated as adjunct treatment in infectious diseases. The effects on innate and adaptive immunity in vivo are insufficiently known. Here, we investigate whether combination treatment with antiretroviral therapy (ART) and Interleukin-2 (IL-2) of patients with primary HIV-1 infection induces sustained increases in circulating NKT cell and NK cell numbers and effector functions and investigate how changes are coordinated in the two compartments. Patients with primary HIV-1 infection starting ART were analyzed for numbers, phenotype and function of NKT cells, NK cells and dendritic cells (DC) in peripheral blood before, during and after IL-2 treatment. NKT cells expanded during IL-2 treatment as expected from previous studies. However, their response to α-galactosyl ceramide antigen were retained but not boosted. Myeloid DC did not change their numbers or CD1d-expression during treatment. In contrast, the NK cell compartment responded with rapid expansion of the CD56(dim) effector subset and enhanced IFNγ production. Expansions of NKT cells and NK cells retracted back towards baseline values at 12 months after IL-2 treatment ended. In summary, NKT cells and NK cells respond to IL-2 treatment with different kinetics. Effects on cellular function are distinct between the cell types and the effects appear not to be sustained after IL-2 treatment ends. These results improve our understanding of the effects of cytokine immunotherapy on innate cellular immunity in early HIV-1 infection.