DAB389IL-2 recombinant fusion toxin effect on lymphocyte- and macrophage-producing cytokine subpopulation cells in experimentally induced demyelinating disease in mice

Abstract

Context: We have reported previously that DAB389IL-2 recombinant fusion toxin targets IL-2R bearing CD4⁺ cells, and suppresses demyelinating disease in acute (A) - and chronic (C) - experimental autoimmune encephalomyelitis (EAE) animal models of multiple sclerosis.

Objectives: The present study was undertaken to investigate the effect of DAB389IL-2 treatment on various cytokine-secreting cell populations in A-EAE and C-EAE mice.

Materials and methods: The effects of DAB389IL-2 at doses of 200-, 800-, or 1600 kU administered i.v. on days 11-13 and 15 on the clinical score and cytokine-secreting cell populations were examined using flow cytometry.

Results: C-EAE mice treated with 1600kU DAB389IL-2, but not A-EAE mice treated with 800 kU had significantly reduced disease. The CD3+CD25+ sub-population in spleens and spinal cords of A-EAE mice treated with 800 kU DAB389IL-2 a was increased, whereas in C-EAE mice treated with 1600 kU this population was increased. DAB₃₈₉IL-2 treatment reduced CD3⁺CD4⁺, CD3⁺CD8⁺, CD4⁺CD8⁺, CD3⁺IL-2⁺, CD3⁺IFN-γ⁺ and CD3⁺TNF-α⁺ T cell subpopulations in the spinal cord in A-EAE, and C-EAE mice on day 16. CD11b+ macrophages that were IL-2-, IFN-γ-, and TNF-α- positive were reduced in A-EAE mice. DAB389IL-2 treatment reduced CD19⁺ B-cells positive for IL-2 or CD11b⁺ in the spinal cord in acute and chronic disease. DAB389IL-2 treatment also reduced lymph node CD3⁺CD8⁺, CD4⁺CD8⁺, CD3⁺CD25⁺ populations on day 16, and lymph node CD3⁺IL-10⁺ and peripheral blood CD3⁺CD25⁺ populations on day 24.

Discussion and conclusions: Our study demonstrates that DAB₃₈₉IL-2 fusion toxin suppresses EAE in a dose-dependent manner, and alters inflammatory cell sub-populations during disease development.

Keywords: DAB389IL-2; Diphtheria toxin; experimental autoimmune encephalomyelitis; interleukin-2 receptor; multiple sclerosis.