1. An expert system for providing treatment information pertaining to a patient receiving FK 506 to prevent an adverse immune response by partially suppressing the patient's immune system without unduly suppressing the ability of the immune system to combat infection, the system comprising: (a) an input means; (b) an output means; (c) a storage means having a knowledge base comprising rules including one of a plurality of treatment instructions in response to at least one of various combinations of a plurality of characterizations which can be assigned to a plurality of patient examination criteria; and an expert computer program including a first routine for prompting, through the output means, a user to enter, through the input means, the characterizations assigned to the patient examination criteria; a second routine for selecting the treatment instruction by locating a rule which covers the characterizations assigned to the patient examination criteria; and a third routine for communicating to the output means the treatment instruction; and (d) a processor.