Yehudith Azar

Immune Regulation and Oxidative Stress Reduction by Preimplantation Factor following Syngeneic or Allogeneic Bone Marrow Transplantation

Bone marrow transplantation (BMT), a well-established treatment for hematological diseases, is frequently hampered by graft-versus-host disease (GVHD) and/or by infections due to delay in immune restoration. Prelmplantation Factor (PIF) is an embryo-derived peptide whose physiological function is to regulate local and systemic immunity and promote transplant acceptance. Synthetic PIF’s effectiveness to regulate immune response following BMT was herein examined in murine model. PIF administration reduced GVHD following allogenic BMT, decreased skin, liver, and colon inflammation and down regulated GVHD-associated gene expression in the liver. iNOS gene expression was reduced both in liver and colon. In syngeneic BMT, PIF administration reduced proinflammatory genes expression and promoted mice weight recovery up to two months after transplantation. PIF immune-regulatory effects were mediated via interaction with monocytes, resulting in decreased iNOS expression and NO secretion in-vitro. Overall, we demonstrate that by regulating immune response after BMT, PIF reduces inflammation and oxidative stress, leading to transplant success.

Antigen-specific murine T-cell lymphomas: Functional heterogenicity

Abstract Two ovalbumin (OVA)-specific helper lymphomas (designated ROT/6.1 and ROT/6.2) were established by transformation of enriched, OVA-immune T cells with the radiation leukemia virus (RadLV). Shortly after establishment these lymphomas provided carrier (OVA)-specific help for anti-hapten antibody response. However, 5 months later ROT/6.1 lost its OVA specificity and could augment anti-hapten antibody response in the presence of an unrelated carrier. ROT/6.2 retained its antigen-specific helper function over 10 months of repeated passaging. This OVA-specific helper line inhibited anti-hapten antibody response when given together with an unrelated carrier. Cloning of ROT/6.2 by limiting dilution revealed that only 3 of 10 clones tested had OVA-specific helper activity. None of the clones could induce antigen-specific DTH reaction. The interrelationship between the functional heterogenicity, specificity, and stability of the helper lines is discussed.

Early cell-cycle gene expression in T-cells after hematopoietic stem cell transplantation

Regeneration of the immune system after hematopoietic stem cell transplantation (HSCT) is a slow process. Early cell cycle proto-oncogenes are key players in the first events of the proliferative process of T-cell immune response. To identify the causes of the prolonged immuno-suppression after transplantation we evaluated the expression of early T-cell cycle genes c-myc, c-jun and c-fos in peripheral blood T-cells from post-transplant patients versus healthy controls before and after phytohemagglutinin (PHA) incubation. Results show that c-jun and c-fos expression continued to increase during the first 18 months post-transplant, and eventually decreased at two years post-transplant. C-myc, c-jun and c-fos expression values also showed a time-dependent increase in surviving patients. In non-surviving patients, however, there was a time-dependent decrease in gene expression. Significant correlation was shown in c-jun expression values of all patients up to 2 years post transplant between resting state and 3h post-PHA incubation when compared to healthy controls. A positive correlation was found in c-fos gene expression between values at resting state and 3h post PHA incubation in patients with Graft versus Host Disease (GVHD) compared patients with no GVHD or healthy controls. A positive correlation was observed between white blood cell count and c-fos expression among non-surviving patients and patients who suffered from GVHD. Our results show that molecular monitoring of the immune reconstitution using c-jun, and c-fos expression combined with clinical parameters may improve the early detection of immune-function failure. This follow-up system may allow for the development of more efficient treatments and new interventions designed to hasten desirable T-cell regeneration.

In vivo helper activity of enriched populations of antigen-specific T lymphocytes

Enrichment of murine antigen-specific T cells was achieved by stimulation of primed lymph node cells with macrophages containing the immunizing antigen. After a week in culture, the in vitro-sensitized lymphocytes had an increased helper activity. Inoculation of 10(7) egg albumin (OVA)-enriched T cells together with hapten coupled to OVA, elevated the number of splenic antihapten-producing cells of primed or unprimed mice. Augmentation of the hapten specific B-cell response could be observed as early as 4 days following the injection of the enriched population and peaked at Day 7. The enhancing effect of the enriched population of antigen-specific T cells was carrier specific since it occurred only in the presence of hapten coupled to the T-cell sensitizer [2,4-dinitrophenol (DNP)-OVA]. When given with the hapten conjugated to an irrelevant carrier [DNP-human gamma globulin (HGG)], the enriched lymphocytes caused a depression in the anti-DNP response. The capacity of in vitro enriched lymphocytes to promote a substantial antigen-specific helper activity (up to 1 anti-DNP producing cell per 10(3) spleen cells) upon adoptive transfer to nonirradiated mice, provides an experimental system for studying B-T collaboration in vivo under the normal physiological conditions.