Characterization of chemokine-fusion proteins. (A) Staining of BALB/c CD11b⁺ splenocytes with vaccine proteins. Both MIP-1α and RANTES maintain binding to CD11b⁺ cells in all 3 fusion protein formats, while the mutation of the first cysteine to serine in MIP-1α and RANTES abrogates binding to CD11b⁺ cells. Bound proteins were detected by fluorochrome-labeled HP6017 mAb that binds hIgG Fc. (B) Vaccibodies with the different targeting and dimerization units all form functional homodimers of approximately 100 kDa, while the monomeric chemokine-scFv protein has a molecular weight of approximately 35 kDa.