Proliferative suppression and class I insufficiency on peripheral blood cells from hepatitis C patients overcome by exogenous cytokines or high-dose mitogen

Mhc polymorphisms fail to explain the heritability of phytohaemagglutinin-induced skin swelling in a wild passerine

Genetic estimates of the variability of immune responses are rarely examined in natural populations because of confounding environmental effects. As a result, and because of the difficulty of pinpointing the genetic determinants of immunity, no study has to our knowledge examined the contribution of specific genes to the heritability of an immune response in wild populations. We cross-fostered nestling house sparrows to disrupt the association between genetic and environmental effects and determine the heritability of the response to a classic immunological test, the phytohaemagglutinin (PHA)-induced skin swelling. We detected significant heritability estimates of the response to PHA, of body mass and tarsus length when nestlings were 5 and 10 days old. Variation at Mhc genes, however, did not explain a significant portion of the genetic variation of nestling swelling to PHA. Our results suggest that while PHA-induced swelling is influenced by the nest of origin, the importance of additive genetic variation relative to non-additive genetic variation and the genetic factors that influence the former in wild populations still need to be identified for this trait.

Cellular immunity impaired among patients on left ventricular assist device for 6 months

BACKGROUND

Sustained maintenance on left ventricular assist device (LVAD) is associated with an increased frequency of severe infections. Although temporary changes in cellular immunity are seen immediately after implantation, the consequence of sustained LVAD treatment on immunity is unknown.

METHODS

In vitro functional and phenotypic markers of T cell activation and 6 month clinical outcome were compared between patients with > or = 6-month LVAD therapy and heart failure control patients.

RESULTS

Recipients of LVADs had more infections (45.5% versus 0%; p < 0.05) and mortality (54% versus 16%; p < 0.05) than control patients. T-cell proliferative responses were lower among LVAD recipients than control patients when challenged with phytohemagglutinin (3.4 +/- 4.7 versus 28.5 +/- 19.6; p < 0.01), anti-CD3 (4.3 +/- 4.5 versus 16.4 +/- 17; p < 0.01), and staphylococcal enterotoxin B (7.2 +/- 6.3 versus 26.1 +/- 15.6; p = 0.002). Proliferative hyporesponsiveness among LVAD recipients was not caused by apoptosis (2.6% +/- 2.7% versus 2.7% +/- 2.1%; p = 0.94) or insufficient CD4+ cells (42.1% +/- 11.3% versus 40.2% +/- 7.5%; p = 0.71) relative to control patients. Instead, CD3+ cells from LVAD patients expressed less interleukin 2 (2.5% +/- 1.5% versus 5.2% +/- 3.1%; p = 0.03) and tumor necrosis factor-alpha (6.0% +/- 3.5% versus 25.8% +/- 8.7%; p < 0.001) and more interleukin 10 (5.8% +/- 6.1% versus 2.6% +/- 2.1%; p < 0.05). In addition, suppressive T-regulatory cells were more prevalent in LVAD patients than control patients (12.9% +/- 3.2% versus 1.2% +/- 1.1%; p < 0.001).

CONCLUSIONS

Cellular immunity is compromised among long-term LVAD recipients because of a downregulatory cytokine imbalance and emergence of suppressive T-regulatory cells.

Quantitation of alloantibody concentration can predict patient sensitivity to intravenous immunoglobulin desensitization

Despite the success of intravenous immunoglobulin (IVIg) desensitization to reduce anti-human leukocyte antigen antibodies, its high failure rate and expense limit its usefulness. We speculated that quantitation of alloantibody concentration could allow early identification of IVIg resistant patients. Patients were described as nonresponders (n=3) or responders (n=8). Panel reactive antibodies (PRA) were determined using Flowbeads and concentration calculated as molecules of equivalent soluble fluorochrome (MESF). PRA was equivalent between nonresponders and responders before (97+/-3% vs. 76+/-20%, P=NS) and after 3 IVIg/plasmapheresis (PP) treatments but lower among responders at end-of-treatment (76+/-20% vs. 44+/-15%, P<0.01). In contrast, pretreatment MESFs were higher (333,640+/-241,352 vs. 38,741+/-5,133, P=0.006) among nonresponders than responders. During treatment, MESFs decreased (P<0.05) in 0 of 3 nonresponders vs. 8 of 8 responders. Final MESFs were higher among nonresponders than responders. We report that quantitation of MESFs allows early identification of IVIg/PP resistant patients. This sensitive and inexpensive technique should allow more effective patient selection and reduce the costs associated with desensitization.

Leucoytapheresis with Adacolumn® enhances HCV-specific proliferative responses in patients infected with hepatitis C virus genotype 1

The most important aim in controlling virus infections is to destroy infected cells. Impaired cellular immunity in HIV and HCV infection leads to chronic infection. This study examined the effect of cytapheresis on the subsequent response to interferon/ribavirin treatment in patients infected with HCV. Adacolumn cytapheresis was carried out once a day for 5 consecutive days in patients who relapsed or did not respond to previous peginterferon and ribavirin combination treatment (n = 14: relapsers = 3, non-responders = 11). Peginterferon and ribavirin combination treatment was started after cytapheresis. During combination treatment, the proliferative response of peripheral blood mononuclear cells to HCV proteins (core, NS3, NS4, and NS5), tetanus toxoid, and phytohemagglutinin was measured, and compared to the early virological response. After treatment by leucocytapheresis, the proliferative response of peripheral blood mononuclear cells to HCV-core and tetanus toxoid increased significantly over the baseline (P < 0.05). A marked increase in the phytohemagglutinin response was observed after peginterferon and ribavirin combination treatment was started (P < 0.01 at week 5 and P < 0.005 at week 13). There were, however, no clear changes in the proliferative response to other antigens. Among the 14 patients, 12 (85.7%) achieved an early virological response by week 13 (12 weeks after the start of combination treatment). After treatment, nine patients (64.3%) had a significant proliferative response to HCV core antigen. Among the nine patients, eight patients (88.9%) achieved early virological response. The results indicate that activation of cellular immunity by leucocytapheresis facilitates an early virological response rate in HCV patients. This new therapy may, therefore, become an additional therapeutic measure for HCV.

Comparison of 125I-interferon-alpha binding to peripheral blood cells from African-Americans and Caucasians with hepatitis C

Interferon-alpha (IFN-alpha) is the major treatment for chronic hepatitis C virus (HCV) infection. Drug resistance is problematic, particularly among African-Americans who typically show poorer clinical outcomes than Caucasians. The reasons for ethnic variation in IFN-alpha sensitivity are not clear. We speculated that African-American insensitivity to IFN-alpha may be mediated by reduced density of the IFN-alpha receptor (IFN-alphaR) or reduced internalization of the IFN-alpha/IFN-alphaR complex. This speculation was evaluated by comparing binding, uptake and release of 125iodine-labelled IFN-alpha (125I-IFN-alpha) to peripheral blood cells from African-Americans and Caucasians with HCV infection and ethnically matched healthy volunteers. Under various in vitro conditions, binding of 125IFN-alpha to surface receptors was equivalent (P = ns) between African-Americans and Caucasians with HCV infection as well as healthy volunteers (P = ns). Similarly, internalization and release of the 125I-IFN-alpha/IFN-alphaR complex was equivalent (P = ns) between African-Americans and Caucasians with HCV infection and healthy volunteers (P = ns). In addition, ethnicity did not influence (P = ns) IFN-alpha suppression of phytohaemagluttinen induced proliferation. However, IFN-alpha therapy of the same patients showed that African-Americans had lower response rates than Caucasians (14%vs 54%, P < 0.0001). In summary, IFN-alpha resistance among African-Americans is not mediated by intrinsic differences in IFN-alpha receptor density or internalization.