Immunogenicity of phospholipase A2 toxins and their role in Streptococcus equi pathogenicity.

Streptococcus equi subsp. equi (S. equi) is the causative agent of strangles, one of the most frequently diagnosed infectious diseases of horses worldwide. Phospholipase A2 toxins (PLA2) cleave phospholipid molecules at position sn-2 contributing to the production of leukotrienes that are important inflammatory mediators. Two homologous phospholipases, SlaA and SlaB are encoded by the S. equi genome suggesting that PLA2 toxins may contribute to its pathogenicity. Here we report the immunogenicity and role of PLA2 toxins during natural and experimental infection of horses with S. equi. The levels of anti-PLA2 specific antibodies in serum from horses naturally exposed to S. equi or without exposure were measured by indirect ELISA. Furthermore, the importance of PLA2 was determined during experimental infection of Welsh Mountain ponies with a mutant strain of S. equi lacking slaA and slaB. Our results show that PLA2 toxins are immunogenic, which supports their production during natural S. equi infection, but that these toxins are not essential for the development of strangles in a susceptible natural host.

qKAT: a high-throughput qPCR method for KIR gene copy number and haplotype determination.

Killer cell immunoglobulin-like receptors (KIRs), expressed on natural killer cells and T cells, have considerable biomedical relevance playing significant roles in immunity, pregnancy and transplantation. The KIR locus is one of the most complex and polymorphic regions of the human genome. Extensive sequence homology and copy number variation makes KIRs technically laborious and expensive to type. To aid the investigation of KIRs in human disease we developed a high-throughput, multiplex real-time polymerase chain reaction method to determine gene copy number for each KIR locus. We used reference DNA samples to validate the accuracy and a cohort of 1698 individuals to evaluate capability for precise copy number discrimination. The method provides improved information and identifies KIR haplotype alterations that were not previously visible using other approaches.

LILRA6 copy number variation correlates with susceptibility to atopic dermatitis.

Leukocyte immunoglobulin-like receptors (LILR) are expressed mostly on myelomonocytic cells where they are mediators of immunological tolerance. Two LILR genes, LILRA3 and LILRA6, exhibit marked copy number variation. We assessed the contribution of these genes to atopic dermatitis (AD) by analysing transmission in 378 AD families. The data indicated that copies of LILRA6 were over-transmitted to affected patients. They are consistent with a contribution of LILR genes to AD. They could affect the equilibrium between activating and inhibitory signals in the immune response.

Post-transplant increase in soluble human leukocyte antigen-G associated with non-severe cardiac allograft vasculopathy.

Cardiac allograft vasculopathy (CAV) is the single most important long-term limitation to heart transplantation. This study aimed to assess the value of monitoring soluble human leukocyte antigen-G (sHLA-G) during the first year post-transplantation to predict the severity of CAV, in 21 out of 77 heart recipients assessed by intravascular ultrasound (IVUS). Serum sHLA-G concentration increased after transplant in recipients free of severe CAV, but decreased in recipients suffering from severe CAV, significant differences between these two groups were found 6 to 12 months post-transplantation. The optimal value of the change in post-transplant sHLA-G for identifying severe CAV was ≥0.062%, which maximized sensitivity (80%) and specificity (100%). Importantly, increases in post-transplant sHLA-G were inversely associated with severe CAV, but directly associated with human cytomegalovirus reactivation. In addition, recipients presenting non-severe CAV or an increased sHLA-G post-transplantation, showed higher numbers of CD8(+)CD28(-) T cells and a down-modulation of CD28 on CD4(+) lymphocytes, which typically identifies CD8(+) regulatory T cells and anergic/tolerogenic T helper cells, respectively. In conclusion, quantification of sHLA-G might offer a complementary non-invasive method for identifying recipients at risk of more severe CAV and who might benefit from earlier preventive therapies, although these results need to be confirmed in larger series.

CD28 and KIR2D receptors as sensors of the immune status in heart and liver transplantation.

Viral infections and cellular acute rejection (AR) condition immunosuppressive therapy and compromise the evolution of allografts. Immune monitoring can be useful for ascertaining rejection and for differentiating allo-reaction from activation induced by infections. This work analyzes the usefulness of monitoring the expression of CD28 and KIR2D receptors in peripheral blood T lymphocytes by flow cytometry, to ascertain the immune response in heart and liver transplant recipients. In both types of transplant, the up-regulation of CD28 in CD4(+) lymphocytes in the periods of greatest AR frequency indicates an effective allo-response, whereas the post-transplantation emergence of circulating CD8(+)CD28(-) and CD8(+)CD28(-)KIR2D(+) T cells correlates with better early clinical results. Cytomegalovirus (CMV) infection, but not hepatitis C virus (HCV) or other infections, abrogated both CD28 up-regulation and CD8(+)CD28(-)KIR2D(+) T-cell expansion. Our results show that monitoring the expression of CD28 and KIR2D receptors on T lymphocytes might be considered as sensors of the immune status of heart and liver recipients.

Divergences in KIR2D+ natural killer and KIR2D+CD8+ T-cell reconstitution following liver transplantation.

Natural killer (NK) and CD8(+) T cells may be active elements in the allograft response, but little is known about their role in liver transplantation. Some of these cells express killer immunoglobulin-like receptors (KIRs), which after binding specific ligands may transmit inhibitory/activating signals. In this study, circulating NK and CD8(+) T cells expressing CD158a/h (KIR2DL1/S1) or CD158b/j (KIR2DL2/3/S(2)) receptors were analyzed in 142 liver recipients by flow cytometry. They were underrepresented in patients before transplantation, but following transplantation, whereas the KIR2D(+) NK subsets experienced a late recuperation (day 365) mainly in C2-homozygous patients developing early acute rejection, recovery of the 2 CD8(+)KIR2D(+) T cells started earlier, showing significant differences on day 365 between patients without acute rejection and those suffering from it (p = 0.004 and p < 0.0001, respectively). These differences were also evident when the human leukocute antigen-C genotypes of the recipient were considered. In conclusion, whereas the late recovery of KIR2D(+) NK cells in C2/C2 patients appears to be linked to acute rejection, the increase in early CD8(+)KIR2D(+) T cells in overall liver recipients correlates with a most successful early graft outcome. Therefore, monitoring of KIR2D(+) cells appears to be a useful tool for liver transplant follow-up.

Expression of HLA molecules on peripheral blood lymphocytes: a useful monitoring parameter in cardiac transplantation.

During the rejection process of cardiac allografts, the expression of HLA antigens increases on various graft tissues, ie, the myocardium and the interstitial structures. However, in this type of transplant there is a paucity of knowledge about HLA expression on recipient cells, such as peripheral blood mononuclear cells. In the present study expression of HLA class I and class II antigens was monitored on peripheral blood lymphocytes prior to and during a 12-month follow-up, using flow cytometry. In our series, the frequency of acute rejection episodes was greater from the fourth to the ninth month after transplantation, coinciding with a reduction in cyclosporine blood levels. At the same time, expression of HLA class I and class II antigens significantly increased among recipients suffering from more severe acute rejection episodes compared with those showing acceptance of their grafts (P < .01). In conclusion, acute rejection episodes in cardiac transplantation were associated with up-regulation of HLA molecules on recipient peripheral blood cells. Monitoring the expression of HLA molecules on peripheral blood lymphocytes may represent an easy, noninvasive practice to individualize immunosuppressive therapy.

Co-stimulation of cultured peripheral blood mononuclear cells from intrinsic asthmatics with exogenous recombinant IL-6 produce high levels of IL-4-dependent IgE.

Asthma is an inflammatory airway disorder, traditionally subdivided into extrinsic, immunoglobulin E (IgE)-mediated, and intrinsic asthma of unknown aetiology. IgE synthesis requires contact between T- and B-cells and a signal provided by interleukin (IL)-4, which can be modulated by IL-6. The objective of this study was to evaluate the effects of IL-4 and IL-6 on total IgE synthesis by peripheral blood mononuclear cells from intrinsic and extrinsic asthmatics. Peripheral blood mononuclear cells from intrinsic and extrinsic asthmatic patients and from healthy subjects were cultured and stimulated with pokeweed mitogen, recombinant IL-4 and IL-6. The IgE level in serum and supernatants was measured by an enzyme-linked immunoassay. Serum IgE was significantly lower in intrinsic asthma than in extrinsic asthma, but significantly higher than in control subjects. IgE production by cultured mononuclear cells from extrinsic asthmatics was not modified after exogenous IL-4 and IL-6 addition. However, intrinsic asthmatics showed enhancement of IgE synthesis in response to IL-4 stimulation, reaching a threefold increase of the spontaneous IgE values, when simultaneous recombinant IL-4 plus IL-6 stimulus was used. Our results indicate that exogenous recombinant interleukin-6 can significantly upregulate the interleukin-4-dependent immunoglobulin E synthesis in intrinsic asthma. This suggests that immunoglobulin E could also play a role in the pathogenesis of intrinsic asthma, in which an interleukin-6 threshold would be critical.

Cytokine serum profiles in allergic and non-allergic asthma. Increased production of IL-10 by non-allergic asthmatic patients.

Studies were undertaken to determine whether differences in serum cytokine balances could be involved in the pathogenesis of allergic and in non-allergic asthma. At this propose, interferon-gamma, tumor necrosis factor-alpha, interleukin-2, interleukin-4, interleukin-6, and interleukin-10 were measured by enzimoimmunoassay. The analysis was performed on 24 allergic and 24 non-allergic asthmatic patients and 16 healthy subjects. IFN-gamma and TNF-alpha, included into the type 1 cytokines, appeared significantly increased in the allergic with respect to the non-allergic asthmatic patients (p = 0.01) and (p < 0.001) respectively, while IL-10, which belongs to the type 2 cytokines, was significantly increased in the non-allergic asthmatic (p < 0.001). The IL-6 analysis did not show any significant difference in either of the study group. The most interesting finding was the high serum IL-10 values detected in intrinsic asthmatic patients, which in turn, suggests that this cytokine could participate in the regulation of different immunological features that occurs in non-allergic asthma, and maybe it could indicate a higher stimulated state of cells in this type of asthma. The data presented in this report show a different cytokine profile in serum from allergic and non-allergic asthmatic patients and denote a stronger prevalence of type 2 cytokines in intrinsic asthma.

In vivo chemoactivation of oyster hemocytes induced by bacterial secretion products.

Movements of tissue hemocytes in the Eastern oyster Crassostrea virginica were monitored and quantified by image analysis of sections following inoculation with agar cores containing Escherichia coli or cell-free medium on which the bacteria had previously grown. Hemocytes respond to the presence of live bacteria by accumulating in widely dispersed areas of tissue surrounding the gut and digestive diverticula. The response is rapid and evident within 40 min, is maximal at 1 hr, and declines by 3 hr after inoculation. Sterile implanted agar cores do not produce a response. Bacteria killed with ozone elicit a response when inoculated together with the medium on which they had grown while bacteria killed by heat or formalin do not. Killed bacteria suspended in saline fail to stimulate hemocyte chemokinesis. Cell-free medium applied externally produces a response equal to that measured with live bacteria inoculated internally. Extraction of bacteria-free medium with hexane does not significantly reduce hemocyte chemokinesis. Digestion of bacteria-free medium with pronase completely eliminates chemokinesis. Molecular filtrates of bacteria-free medium induce maximal chemokinetic response at molecular weight as low as 1 kDa. These data show that the oyster hemocyte activators produced by E. coli are most likely low-molecular-weight polypeptides which diffuse from the site of inoculation and can pass through the intact external surface epithelium to induce a chemokinetic response.

Soluble CD23 (sCD23) serum levels and lymphocyte subpopulations in peripheral blood in rhinitis and extrinsic and intrinsic asthma.

To determine serum levels of IgE and sCD23 and lymphocyte subpopulations, we studied 37 control subjects and 84 patients (27 with allergic rhinitis, 27 with extrinsic asthma, and 30 with intrinsic asthma). A rise in surface CD23 on B and monocyte cells and sCD23 serum levels was exhibited by patients with rhinitis and extrinsic asthma. Unexpectedly, in intrinsic asthmatic patients, high CD23 expression on monocytes and high sCD23 levels were seen that did not result in IgE production. It appears that CD23, in its soluble form, could be a good disease marker, especially in asthma. Atopic patients yielded a significantly lower proportion of CD4+ T cells than intrinsic asthmatic patients and normal persons. Otherwise, CD4+CD29+CD45RA- and CD4+CD29-CD45RA T-cell subsets were significantly decreased in all patient groups.

Results of prenatal alcohol exposure on the dimensions and binucleation of cardiac myocytes in neonatal and weanling rats.

Sprague-Dawley rats were exposed to ethyl alcohol in utero. The effect of chronic prenatal exposure was examined by giving mature females alcohol in isocaloric liquid diets which served as the sole source of liquid and caloric intake before mating and throughout gestation. Controls consisted of females maintained on laboratory chow or an isocaloric liquid diet minus alcohol before and during gestation. The offspring were sacrificed at 21 days of age (weanlings) and the hearts dissociated enzymatically to give purified cardiac myocytes. The effects of daily acute prenatal alcohol exposure were studied by gastric intubation of alcohol to chow-fed females for the duration of pregnancy. The doses used approximated 4 and 5 shots of 80 proof liquor per day by a person weighing 150 lb. These offspring were sacrificed at 2, 6, and 21 days postnatal and cardiac myocytes prepared as above. Heart weights were determined and cardiac myocytes were analyzed for cell length, volume, cross-sectional area, and percent binucleation. Additionally, nuclear DNA content was measured in all of the 21 day offspring. Statistical analysis of the data showed no significant differences between hearts exposed to prenatal alcohol and nonexposed controls with either regimen with the exception of percent binucleation which was significantly but only slightly higher in the 6-day-old hearts. These findings are discussed in relation to anatomical heart defects found in patients with full fetal alcohol syndrome.

Nuclear size and DNA content in rat cardiac myocytes during growth, maturation and aging.

Changes in nuclear volume and DNA content were examined in cardiac myocytes isolated from 21-day-old (weanling, W), 3-month-old (adult, A), and 2-year-old (old, O) rats to document normal parameters for nuclear growth and DNA content. Nuclear volume was calculated from direct measurements of isolated myocyte nuclear profiles and DNA content was measured from DAPI-stained nuclei using an image analysis microdensitometry system. Myocyte volume was measured with a Coulter Channelyzer system. Nuclear volume increased 79% from W to A as a result of an increase in nuclear length. Nuclear width was unchanged. Nuclear volume was not changed from A to O. Approximately 98% of the left ventricular myocytes from all three rat groups contained a diploid DNA content with the remainder of nuclei being tetraploid. The degree of polyploidy increased slightly, but significantly, in right ventricular myocytes from O. Due to the substantially greater increase in myocyte volume relative to nuclear volume, nuclear volume percentage decreased from 3.65 +/- 0.28 to 1.64 +/- 0.13 from W to A but was unchanged from A to O. To summarize: (1) nuclear volume of rat cardiac myocytes increases significantly during normal physiological growth (W to A) but the rate of nuclear growth is less than that of cell volume; (2) the increase in nuclear size from W to A is not due to an increase in DNA content; (3) cardiac myocytes from Sprague-Dawley rats are predominantly diploid; and (4) there is little change in DNA content of cardiac myocytes from rats of this strain during growth, maturation and aging.

Hypoploidy and hyperplasia in the developing brain exposed to alcohol in utero.

Prenatal effects of acute maternal alcohol ingestion on chromosome segregation and mitotic frequency in the brain cells of the fetus were evaluated in mice by direct chromosome and mitotic counts and by flow cytometry. Fetuses were exposed to acute transplacental doses of alcohol for 4 days and killed on the fifth day. Those litters in which the fetuses were developed to the equivalent of normal 16th-17th-day gestation age were analyzed. A marked increase in the number of hypoploid metaphases was observed in direct proportion to the dose ingested by the mother. An over 30% increase in hypoploidy over controls was measured in the fetuses exposed to the highest dose. Counts of mitotic cells showed an over tenfold increase in the mitotic index of the fetal brain exposed to alcohol. Flow cytometric measurements of DNA content in isolated fetal brain cell nuclei showed a shift from a single G0/G1 peak in controls to a bimodal G0/G1-G2 + M distribution in alcohol-exposed fetuses of the same developmental age.

Cytometric investigations on hemocytes of the American oyster, Crassostrea virginica.

Pericardial hemolymph was obtained from American Oysters (Crassostrea virginica) and the hemocytes characterized by flow cytometry. The cells were found to have a broad unimodal size distribution with a median diameter of 7 micrometers. Total protein measured by flow cytometric fluorescence of dansylated cells also revealed a broad unimodal distribution similar to that obtained for size. The proportion of hemocytes in each stage of the cell cycle was measured using DNA-specific DAPI fluorescence. Histograms showed a single peak representing the G(0)/G(1) population. There was no evidence of S or G(2)+M phases of the cell cycle, nor was polyploidy seen. The forward and orthogonal light scatter of fixed hemocytes showed no evidence of sub-populations on the basis of cytoplasmic granularity. Thus, in terms of these parameters, oyster hemocytes appear to represent a single population exhibiting graded cellular differences.

Cytological evidence of transient sex chromatin decondensation during compensatory hypertrophy in rat livers.

The left lateral lobes were surgically removed from livers of female rats. The number of cells containing sex chromatin bodies was counted in the surgically removed lobes and compared with counts from the remaining lobes removed at various intervals after the operation. The proportion of cells showing positive sex chromatin was found to decrease to nearly one-half the initial preoperative value by four days after partial hepatectomy. Sex chromatin frequency returned to near preoperative levels by 21 days. A 3H-thymidine autoradiography showed that the number of cells in the S-phase was less than 5 percent at the postoperative time when sex chromatin frequency was lowest, thus ruling out the possibility that the decreased numbers of sex chromatin positive cells was related to genome replication. These data show that condensation of the late-replicating, and, presumably, inactive X-chromosome is not permanent, a fact that may relate to X-inactivation observed in embryogenesis.

Numerical chromosome variation in mouse spermatogonia resulting from alcohol consumption.

Male mice were force fed ethyl alcohol intragastrically at increasing daily doses. The animals were killed at various times after the initiation of alcohol ingestion. Chromosome numbers per cell were counted from spermatogonial mitoses and compared with those from controls that were not exposed to alcohol. An average of 16 percent of the spermatogonial mitoses from alcohol ingesting animals had hypodiploid numbers (usually 2n-1) compared to 6 percent in the control animals. No correlation between the total amount of alcohol consumed and the number of hypodiploid spermatogonia was noted.