The spleen is the major site for the development and expansion of inhibitor producing-cells in hemophilia A mice upon FVIII infusion developing
high-titer inhibitor.
Thromb Res 2023;
231:144-151. [PMID:
36948993 DOI:
10.1016/j.thromres.2023.03.003]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/22/2023] [Accepted: 03/13/2023] [Indexed: 03/19/2023]
Abstract
BACKGROUND
Hemophilia A (HA) is a hereditary bleeding disorder caused by defects in endogenous factor (F)VIII. Approximately 30 % of patients with severe HA treated with FVIII develop neutralizing antibodies (inhibitors) against FVIII, which render the therapy ineffective. The managements of HA patients with high-titter inhibitors are especially challenging. Therefore, it is important to understand the mechanism(s) of high-titer inhibitor development and dynamics of FVIII-specific plasma cells (FVIII-PCs).
AIMS
To identify the dynamics of FVIII-PCs and the lymphoid organs in which FVIII-PCs are localized during high-titer inhibitor formation.
METHODS AND RESULTS
When FVIII-KO mice were intravenously injected with recombinant (r)FVIII in combination with lipopolysaccharide (LPS), a marked enhancement of anti-FVIII antibody induction was observed with increasing FVIII-PCs, especially in the spleen. When splenectomized or congenitally asplenic FVIII-KO mice were treated with LPS + rFVIII, the serum inhibitor levels decreased by approximately 80 %. Furthermore, when splenocytes or bone marrow (BM) cells from inhibitor+ FVIII-KO mice treated with LPS + rFVIII were grafted into immune-deficient mice, anti-FVIII IgG was detected only in the serum of splenocyte-administered mice and FVIII-PCs were detected in the spleen but not in the BM. In addition, when splenocytes from inhibitor+ FVIII-KO mice were grafted into splenectomized immuno-deficient mice, inhibitor levels were significantly reduced in the serum.
CONCLUSION
The spleen is the major site responsible for the expansion and retention of FVIII-PCs in the presence of high-titer inhibitors.
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