7B. The DAPT in vitro X axis of this figure should have read: negative, flu, HIV. The figure has been correctly reproduced below: “
“Peripheral

blood mononuclear cells (PBMC) are important for the development of immune based therapies and clinical vaccine studies. An increasing number of investigations focus on diseases affecting cellular immunity, including HIV (Torresi et al., 2004 and Mlotshwa et al., 2010), tuberculosis (Sester et al., 2010) and cancer (Gilboa, 2004), using PBMC for assay readout. Changes in the antigen-specific T-cell response indicate the efficiency of a new test vaccine as it affects the initiation of antibody synthesis. However, the time slot for reliable results after PBMC isolation is quite narrow (Bull et al., 2007). This makes

comparison of results difficult between laboratories and, following Luyet and Hodapp, 1938, new cryopreservation methods have been continuously developed. At temperatures below − 130 °C, metabolic activity is significantly reduced and cells can theoretically be kept for long periods without effects on properties and function (Hunt, 2007). Effective and reproducible cryopreservation protocols for PBMC enable the setup of large sample repositories, allowing retrospective monitoring in pathogenesis studies and inter-laboratory controls of assay outcomes. Today, most active phase II/III vaccine studies already bank cells from all participants to allow repeated analysis of the immunological

response at different points of time. Suboptimal cryopreservation results in a significant decrease of cell viability and number, and may also cause alterations of the cellular phenotype learn more and a reduction of the immunogenic response to specific antigens (Costantini et al., 2003). Therefore, the use of cryopreserved PBMC in functional assays has to be validated and cryopreservation protocols have to be adapted to guarantee reliable and reproducible results. A wide range of studies have already been performed, Thiamine-diphosphate kinase analyzing the effects of freezing and thawing on PBMC. Most results showed only minimal effects on the viability of cells (Birkeland, 1980, Sobota et al., 1997 and Hayes et al., 2002), with a clear correlation of viability and T-cell function in lymphocyte assays (Reimann et al., 2000 and Weinberg et al., 2000). However, preservation of antigen-specific T-cell response is under permanent critical discussion. Some studies found no significant difference between fresh and frozen cell responses to recall antigens (Kreher et al., 2003, Maecker et al., 2005 and Disis et al., 2006), whereas others reported an increase in frozen samples (Weinberg et al., 1998) or reduced function in lymphocyte assays against HIV p24 and CMV antigens, as well as against mitogens (Costantini et al., 2003, Miniscalco et al., 2003 and Owen et al., 2007) after cryopreservation. Further studies on antigen-specific T-cell response are necessary to evaluate these results.