Fluorescent antigen method is well-known. You could label horse ferritin with FITC and see the attachment on the membrane of macrophage or antigen-presenting cells. You may find out some difficulty with albumin. You must separate FITC-labeled albumin and free alubumin with SEFADEX. If you could not isolate FITC-labeled albumin, then you must select some other protein in horse serum.Fujiwara S. Studies on antibody production to horse ferritin in mice. I. Origin of the antibody-producing cells. Jpn J Exp Med. 1969 Oct;39(5):461-70. could be nice paper. Although this is old paper, this was performed by graduate student.