Objective

1. Recovery from autoimmunity of MRL/lpr mice after infection with an interlukin-2/vaccinia recombinant virus • Guitierrez J, Andreu J, Revilla Y, Vinuela E, Martinez C. Recovery from an autoimmunity of MRL/lpr mice after infection with an interlukin-2/vaccinia recombinant virus. • Presented by: Colleen Leonard

2. Objective • Examine the effects of IL-2 on the disease progression in MRL/lpr mice using live vaccinia recombinant viruses

3. MRL/lpr mice- strain of systemic lupus erythematosus in mice that develops early in life. • SLE- autoimmune disease of humans usually involving anti-nuclear antibodies. • Autoimmunity- immune recognition and reaction against the individual’s own tissues. • IL-2- a molecule involved in signaling between cells of the immune system. Specifically a T-cell derived molecule implicated in the clonal expansion of antigen-activated T cells and in T-cell development.

4. Antigen- any molecule that can be specifically recognized by the adaptive elements of the immune system. • Antibody- molecule, produced by animals in response to antigen, that has a particular property of combining specifically with the antigen that induced it’s formation • T cells- lymphocytes that differentiate primarily in the thymus and are central to the control and development of immune responses. • CD4+T cells- helper cells which recognize an antigen in association with MHC Class II molecules.

5. CD8+T cells- cytotoxic cells that recognize antigens in association with MHC class I molecules. • MHC (major histocompatibility complex)- a set of genes found in all mammals whose products are primarily responsible for the rapid rejection of grafts between individuals, and function in signaling between lymphocytes and cells presenting antigen. • CD3-required for signal transduction following antigen recognition by the TCR heterodimer.

6. Rate of survival • MRL/lpr mice infected with IL-2/vaccinia survived for more than a year compared with MRL/lpr mice treated with saline or infected with wild-type vaccinia.

7. Rate of Survival

8. Clinical Symptoms • Survival was also accompanied by a lack of clinical symptoms such as arthritis, cutaneous ulcers and general deteritoration present in normal lpr mice was barely detectable after treatment. • The raised protein levels found in urine of non-infected MRL/lpr mice and MRL/lpr mice infected with wild type vaccinia virus, were significantly decreased in the recombinant-treated group.

9. Infiltration in kidney • Massive interstitial infiltration of the MRL/lpr kidney of the mouse infected with wild-type vaccinia. • Minimal mononuclear infiltration in kidney in the recombinant-treated mouse.

10. Glomerular size and cellularity • Increase in glomerular size and cellularity in the wild-type-infected mice. • The intraglomerular proliferation as well as glomerular enlargement were absent in kidneys from recombinant-infected mice.

11. Infiltration in synovial membrane • Massive mononuclear infiltrate in wild-type-infected mice. • Absence of mononuclear infiltrate in recombinant infected mice.

12. Pre-T stem cell development • MRL/lpr disease is a result of a defect in pre-T stem-cell differentiation requiring thymus influence for the development of the full blown syndrome. • This syndrome is associated with the expansion of phenotypically immature double-negative cells as well as a marked decrease of immature ‘double positive’ thymocytes.

13. T-cell development

14. Cytometric analysis of thymocytes • Thymuses from recombinant-infected mice showed a significant reduction in double-negative cells accompanied by a three-fold increase in the immature double-positive CD4+CD8+ population.

15. Intrathymic differentiation-maturation • These data support the assertion that the IL-2/vaccinia recombinant treatment promotes the intrathymic differentiation-maturation of early T-cell precursors, resulting in a threefold expansion of CD4+ and CD8+ cells.

16. Accumulation of double-negative cells • Control mice showed hyperplasia of peripheral lymphoid organs produced by the accumulation of lymphocytes of phenotype CD3+CD4-CD8-. • Spleen, lymph node, and peritoneal cells were stained with anti-CD3, anti-CD4 and anti-CD8 monoclonal antibodies.

17. Cytometric analysis showing the reduction of CD3+CD4-CD8-

18. Spleen • Amount of CD3+ double-negative cells was reduced in the recombinant infected mice (from 20% to 3%). • Higher levels of mature cells (both CD4+CD8- and CD4-CD8+).

19. Lymph node • Amount of CD3+double negative cells was reduced in the recombinant infected mice (from 59% to 10%). • Higher levels of mature cells (both CD4+CD8- and CD4-CD8+).

20. Peritoneal cells • Amount of CD3+double negative cells was reduced in the recombinant infected mice (from 17% to 4%). • Higher levels of mature cells (both CD4+CD8- and CD4-CD8+).

21. Conclusion • Vaccinated mice showed prolonged survival, marked attenuation of kidney interstitial infiltration and intraglomerular proliferation, as well as clearance of synovial mononuclear infiltrates. • Inoculation with the IL-2/vaccinia recombinant virus led, in addition, to drastic reduction of the double negative T-cell population, improved thymic differentiation and restoration of normal values of mature cells in peripheral lymphoid organs.

22. References • Boes M, Schmidt T, Linkemann K, Beaudette B, Rothstein A, and Chen J. Accelerated development of IgG autoantibodies and autoimmune disease in the absence of secreted IgM. PNAS. Vol 7:1184-1189. Feb. 2000. • Finck B. Linsley P, Wofsy D. Treatment of Murine Lupus with CTLA4Ig. Science Vol. 265 :1225-1227. August 1994. • Gutierrez J, Andreu J, Revilla Y, Vinuela E, Martinez C. Recovery from autoimmunity of MRL/Ipr mice after infection with an interlukin-2/vaccinia recombinant virus. Nature Vol. 346:271-274. July 1990. • Roitt I, Brostoff J, and Male D. Immunology-Fifth Edition. 1998 Mosby International Ltd.