Tracking of specific CD4⁺ T cells following FVIII administration. CD4⁺ T cells from OT-II mice, which recognize an immunodominant OVA peptide that was engineered into a FVIII-OVA hybrid protein, were labeled with cell trace violet. These cells were then adoptively transferred into transgenic C57BL/6-CD11c-DTR/GFP mice, which were subsequently injected intradermally with 5 μg of FVIII-OVA 1, 5, or 20 hours before performing IVM of the draining lymph node. The violet T cells initially entered the green (CD11c⁺GFP⁺) T-cell zone, and by 20 hours after FVIII-OVA injection, most of these cells were clustered at the T-B cell zone at the border of B-cell follicles. This trafficking pattern suggested they had differentiated into T-follicular cells by 20 hours after exposure to FVIII-OVA. DTR, diphtheria toxin receptor; GFP, green fluorescent protein.