Cloning and chromosomal assignment of the porcine interleukin-2 receptor alpha (IL-2Ralpha) gene

Effects of porcine reproductive and respiratory syndrome virus-infected antigen-presenting cells on T cell activation and antiviral cytokine production

The ability of porcine reproductive and respiratory syndrome virus (PRRSV) to suppress T cell expression of CD25 (alpha chain of interleukin [IL]-2 receptor), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) was determined by flow cytometry in naive porcine T cells in response to mitogen (concanavalin A) and cytokine inducers (phorbol 12-myristate 13-acetate plus ionomycin [PMA/I]). Four PRRSV isolates of varying clinical virulence and three different types of porcine myeloid antigen-presenting cells (APCs) were used. T cells cultured with monocytes infected with virulent PRRSV (VR-2385, SDSU-73, and VR-2332), but not with a vaccine strain (Ingelvac PRRS MLV; Boehringer Ingelheim Vetmedica, St. Joseph, MO), demonstrated significantly reduced CD25 expression (%CD25(+)) and IFN-gamma expression (%IFN-gamma (+)) compared with T cells incubated with uninoculated monocyte cultures. T cells cultured with monocytes infected with all four PRRSV isolates demonstrated significantly reduced %TNF-alpha (+). The significant reduction of %CD25(+), %IFN-gamma (+), and %TNF-alpha (+) was not detected in T cells cultured with monocyte-derived macrophages (MDMs) and immature monocyte-derived dendritic cells (MDCs) infected with any PRRSV isolates. Heat-inactivated PRRSV did not induce significantly reduced T cell responses in any APC cultures. The reduction of T cell response in monocyte cultures was not due to PRRSV-induced T cell death. Gene expression of IL-10 detected by semiquantitative reverse transcriptase-polymerase chain reaction was significantly increased in virulent PRRSV-infected monocyte cultures after PMA/I, but not concanavalin A, stimulation compared with IL-10 gene expression from uninoculated monocyte cultures. Increased IL-10 gene expression contributed to significantly reduced %IFN-gamma (+) and %TNF-alpha (+), but not %CD25(+), as determined by IL-10 neutralization assay. This study reports that PRRSV has the ability to suppress T cell responses. The suppressive ability of PRRSV is associated with viral virulence and is mediated by virus-infected monocytes, but not by virus-infected MDMs and immature MDCs.

The roles of IL-12 in providing a third signal for clonal expansion of naive CD8 T cells

Stimulation of an effective in vitro or in vivo response by naive CD8 T cells requires three signals: TCR engagement, costimulation/IL-2, and a third signal that can be provided by IL-12. In addition to being required for acquisition of cytolytic function, IL-12 is required for optimal IL-2-dependent proliferation and clonal expansion. In experiments examining in vitro stimulation of naive CD8 T cells, IL-12 is shown to stimulate expression of the IL-2R alpha-chain (CD25) to much higher levels than are reached in response to just TCR and costimulation and/or IL-2. In addition, high CD25 expression is substantially prolonged in the presence of IL-12. As a consequence, the cells proliferate more effectively in response to low levels of IL-2. Examination of adoptively transferred TCR transgenic CD8 T cells responding to peptide Ag confirmed that IL-12 up-regulates CD25 in vivo, even when B7-mediated costimulation is largely blocked. TCR- and IL-2-dependent proliferation of CD8 T cells from mice deficient in CD25 was also found to increase in the presence of IL-12, indicating that CD25 up-regulation is not the only mechanism by which IL-12 increases clonal expansion of the cells. IL-2 and IL-12 both act to increase expression of both CD25 and the IL-12R, thus providing positive cross-regulation of receptor expression. These results suggest that when cross-priming dendritic cells present class I/Ag and costimulatory ligands, and produce IL-12, naive CD8 T cells will begin to produce IL-2 and both receptors will be optimally up-regulated to insure that an effective response is generated.

Alignment of VIM, MRC1, GAD2, and IL2RA genes on swine chromosome 10q by in situ hybridization and RH mapping

Since the distal half of swine chromosome (SSC) 10q was shown to contain a quantitative trait locus (QTL) influencing swine growth, the precise correspondence between this chromosome region and the orthologous human chromosome region (HSA10p) was investigated using chromosomal fluorescence in situ hybridization and RH mapping of type I loci spanning the growth QTL. The goal was to align this critical region of swine with the corresponding region in human for the purpose of identifying candidate genes. The HSA10p type I loci mapped in swine were VIM, MRC1, GAD2, and IL2RA. Locus order on SSC10q was shown to be centromere-VIM-MRC1-GAD2-IL2RA, while in human the order is centromere-GAD2-MRC1-VIM--IL2RA, indicating that the chromosome segment marked by VIM, MRC1 and GAD2 has been inverted relative to the centromere and IL2RA.

Monoclonal antibodies putatively recognising activation and differentiation antigens

In the activation/maturation section, 46 monoclonal antibodies (mAbs) were analysed using freshly isolated as well as mitogen activated and recall antigen re-stimulated cells. A total of 10 internal standards as well as 6 antibodies with established reactivity for human cells, reported to cross-react with porcine leukocytes, were included in the panel. The standard antibodies were anti-CD25, CD44, CD45, SLA II, SWC1, SWC2, SWC7 and SWC8 reagents. The test panel contained antibodies with putative reactivity to CD25, SLA II and other mAbs directed against ill-defined targets. Single and double colour surface staining was performed in the attempt to group the mAbs tested into clusters of differentiation. Five new anti-class II reagents, two directed to SLA-DQ and three to SLA-DR, could be added to the previously established ones. One new anti-CD25 as well as two new antibodies with SWC7 and SWC8 specificities, respectively, could also be added to the previously established ones. The identity of the two latter antibodies was also confirmed in other sections of this workshop (B-cell section for SWC7 antibodies and myeloid section for the SWC8 antibodies). The antibody JM2F12, in our hands, has shown strong similarities to the cross-reactive anti human-CD49f reagent. No other clusters were identified, as all remaining antibodies behaved in a different way on different target leukocyte populations. The second purpose of the section was fulfilled: interesting staining profiles of several antibodies on differentiating lymphocytes were recorded and are discussed here.