The impact of rhVWF on subsets of FVIII-sensitized CD4⁺T-cell proliferation in response to rhF8 restimulation. Splenocytes isolated from rhF8-immunized FVIII^null mice were labeled with CellTrace Violet and cultured with rhF8 with or without rhVWF for 96 hours. Cells were stained with anti–mouse CD4, TCRβ, CD44, and CD62L and analyzed by flow cytometry. A subset of CD4⁺ T cells was gated and analyzed for daughter cells. (A) CD4⁺ T-cell proliferation. (B) Activated CD4⁺ (CD4⁺CD44⁺) T-cell proliferation. (C) Central memory (CD4⁺CD44⁺CD62L⁺) T cell proliferation. (D) Effector CD4⁺ (CD4⁺CD44⁺CD62L⁻) T-cell proliferation. The paired Student t test was used to compare data sets. These data demonstrate that VWF can attenuate FVIII-sensitized effector as well as central memory CD4⁺ T-cell proliferation in response to rhF8 restimulation.