101. Anti-CD20 treatment depletes B-cells in blood and lymphatic tissue of cynomolgus monkeys.
- Author
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Schr¨oder, Carsten, Azimzadeh, Agnes M., Guosheng Wu, Price, James O., Atkinson, James B., and Pierson, Richard N.
- Subjects
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CD antigens , *B cells , *TRANSPLANTATION immunology - Abstract
Introduction: Macaque species offer a valuable model for translational allo-transplantation and tolerance studies. Cardiac allograft vasculopathy in Macaca fascicularis is associated with elaboration of anti-donor antibodies. Since T-independent pathways of B cell activation have been described, and anti-B cell strategies have proven to be a fruitful tolerogenic adjunct in rodent and xenogenic models, here we investigate whether an anti-CD20 antibody (rituximab) would be useful to deplete B-cells in a preclinical allo-transplantation setting in macaques. Methods: Three cynomolgus macaques which had previously rejected a cardiac allograft and one with concurrent subacute vascular rejection were treated weekly with rituximab 20 mg/kg IV for 4 and 2 weeks, respectively. B-cell levels (CD19 + cells) were measured by flow cytometry in peripheral blood, spleen, lymph node and bone marrow cells at various intervals after initiation of treatment. B-cells and plasma cells were also analyzed by immunohistochemistry at necropsy in spleen, lymph node, tonsil and thymus tissue sections. Anti-donor antibody titers were measured by flow cytometry. Results: B-cells expressing CD19 were not detectable in the peripheral blood in any animal within 24 h after initial treatment, or over the ensuing month. At necropsy, the germinal centers in spleen and lymph node were completely depleted of CD20 + B-cells in 2 animals, leaving a hypocellular trabecular pattern around preserved plasma cell follicles. Substantial but incomplete depletion of B-cells was demonstrated in the other 2 animals, in each instance immunohistochemical findings in spleen and lymph node exhibiting higher sensitivity for residual B-cells compared to FACS. Anti-donor antibody titers exhibited kinetics similar to untreated animals over this short follow-up. Comment: Treatment with anti-CD20 very efficiently depletes peripheral and tissue B-cells but not plasma cells in this macaque species. Biopsy of lymph node is necessary and may be sufficient to assess B-cell clearance in secondary lymphoid organs in this model. [ABSTRACT FROM AUTHOR]
- Published
- 2003