It is intended to provide a method whereby a plural number of antibodies against
cell surface antigens are quickly classified and to provide a method whereby antigens of the thus classified antibodies are quickly identified. Further, it is intended to provide a method of promoting the utilization of the useful data obtained by the above methods. Furthermore, it is intended to provide an
antibody which is effective in treating or diagnosing
cancer. Namely, a method of classifying antibodies which comprises: (1) the step of preparing a plural number of antibodies respectively recognizing
cell surface antigens; (2) the step of bringing each of these antibodies into contact with a
cell of the same species; (3) the step of analyzing each of the cells having been treated in the step (2) by
flow cytometry and thus obtaining data indicating the reactivity of each
antibody with its cell surface
antigen; and (4) the step of comparing the thus obtained data and classifying the individual antibodies depending on the similarity. A method of identifying antigens which further comprises: (5) the step of selecting one to several antibodies from each
antibody group formed in the step (4) and identifying antigens thereof; and (6) on the assumption that antigens of the antibodies belonging to a single antibody group are the same or highly related to one another, making relations between the antigens having been identified in the step (5) and the antibody groups to thereby identify the antigens. An antibody against HER1, an antibody against HER2, an antibody against CD46, an antibody against ITGA3, an antibody against ICAM1, an antibody against ALCAM, an antibody against CD147, an antibody against C1qR, an antibody against CD44, an antibody against CD73, an antibody against EpCAM and an antibody against HGFR, each obtained by using the above methods.