Abstract: The present invention discloses a reliable and efficient method of generating an antibody which can discriminate between the membrane bound form of an antigen and the soluble form of the same antigen. Said method comprises the steps of: (i) immunizing an animal with a first antigen which comprises either the membrane bound form or the soluble form of the antigen; (ii) administering to the animal an agent which selectively kills rapidly dividing cells; (iii) when the first antigen of step (i) comprises the soluble form, immunizing the animal with a second antigen which comprises the membrane bound form of the antigen, or when the first antigen of step (i) comprises the membrane bound form, immunizing the animal with a second antigen which comprises the soluble form of the antigen; and (iv) screening for an antibody which can bind to the second antigen but which does not bind to the first antigen.