Parenteral administration of an activating monoclonal antibody to the α1ß1 integrin in dogs

Ilan Bank, Izhar Hardan, Evgenia Lokshin, Devora Nas, Shmuel Miron, Daniel Ohad, Suzanne Spong, David R. Garrod

Research output: Contribution to journalArticlepeer-review

Abstract

In mice, monoclonal antibody (mAb) to the α1 integrin abrogate gastro-intestinal damage during graft-versus-host-disease (GVHD), suggesting anti α1 mAb as candidates for treatment in humans as well. Our current data show that one such reagent, mAb 1B3.1, when immobilized to plastic wells via rabbit- anti murine (ram) immunoglobulin (Ig) induces a protein kinase-dependent spreading of activated human T cells. Furthermore, it significantly increases the proliferative response, and expression of interleukin-2 (IL-2) receptors (R) and CD69, of resting T cells, expressing minimal integrin on the cell surface, to sub-optimal stimulation by anti-CD3 mAb. We found, in addition, that mAb 1B3.1 a) immuno-precipitates α1ß1 integrins from cell-surface iodinated canine epithelial cells b) is highly reactive with canine T cells after their activation and c) inhibits adhesion of canine T cells to collagen IV. Despite the potential ability of the mAb to co-activate T cells in vitro, two dogs that received 4 injections of 0.5-0.3 mg/Kg of mAb 1B3.1 remained healthy, developing only marginal transient lymphopenia. Injection of 0.75mg/Kg in a third dog induced a more marked lymphopenia, and an additional dose of 1.0 mg/Kg 2 weeks later was followed by gastrointestinal hemorrhage. Importantly, the lymphopenia was associated with a greater and more persistent decrease of CD8+ than of CD4+ T cells, leading to an increase in the CD4/CD8 ratio 24 hours after the injection. Thus, despite it's co-activating effects in vitro, administration of this mAb in vivo is feasible when appropriately dosed, and may have immuno-modulatory effects.

Original languageEnglish
Pages (from-to)239-253
Number of pages15
JournalImmunobiology
Volume202
Issue number3
DOIs
StatePublished - 1 Sep 2000
Externally publishedYes

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