Cytofluorometry analysis demonstrating the specific coating of anti-tumor Fab-HLA-A2/Flu conjugates on the surface of HLA-A2 negative tumor target cells, using a FITC-labeled anti-HLA-A2 mAb. (A) CEA positive colon carcinoma cells LoVo. (B) ErbB-2 positive breast carcinoma cells SK-BR-3. (C) CD20 positive B lymphoma cells Daudi were incubated with anti-CEA Fab-HLA-A2, anti-ErbB-2 Fab-HLA-A2 or anti-CD20 Fab-HLA-A2 conjugates respectively, followed by FITC-labeled anti-HLA-A2 (thick solid histograms) or with the latter conjugate alone (grey shaded histograms).