A diagnostic skin test for predicting treatment outcome, consisting essentially of an effective amount of an NCM or a T lymphocyte mitogen of muromonab-CD3. A kit for performing a skin test consisting essentially of an effective amount of an NCM or a T lymphocyte mitogen of muromonab-CD3. A method of performing a skin test on a patient, consisting essentially of the steps of administering an effective amount of an NCM or a T lymphocyte mitogen of muromonab-CD3 to skin, analyzing results of the skin test, and predicting a treatment outcome. Methods of detecting defects in monocyte or T lymphocyte function, including the steps of administering an effective amount of an NCM or T lymphocyte mitogen of muromonab-CD3 to skin, analyzing results of the skin test, and detecting at least one defect in monocyte or T lymphocyte function. A mechanism for indicating a functioning efferent or afferent limb of an immune system, including a diagnostic skin test including an effective amount of an NCM or a T lymphocyte mitogen of muromonab-CD3.
