Several types of cells to be tested or several types of cell antigens to be tested can be detected simultaneously with high sensitivity in a simple way by reacting the cells or antigens with several types of fine particles which are optically distinguishable and to which antibodies adhere, where the antibodies react specifically with the cells or antigens; and subsequently detecting the cells or antigens by an optical device which permits grading of the individual fine particles. Several types of cells to be tested or several types of cell antigens to be tested can also be detected by reacting the cells or antigens with antibodies which in each case react specifically with the cells or antigens; subsequently reacting therewith antibodies which adhere to several types of fine particles which are optically distinguishable, where these antibodies react specifically with the abovementioned antibodies; and subsequently detecting the cells or antigens by an optical device which permits grading of the individual fine particles.
