Results obtained from comparative analysis of ICO-G2 monoclonal antibody with some standard CD 15 monoclonal antibodies (FMC-11, TG-1, G-2, B-3-4) and with MG-1, MG-3, MG-5, MG-6 monoclonal antibodies (Prague) performed by flow cytometry on FACS 440 instrument (Becton Dickinson) indicate that all monoclonal antibodies have a similar reactivity and may identify the same X-haptene structure (also known as Lex) included into the differentiation cluster as CD15.