Adjuvant activity of incomplete Freund's adjuvant.

The water-in-oil emulsion adjuvants developed by Jules Freund and coworkers have been, and continue to be, used in research and veterinary vaccines. Incomplete Freund's Adjuvant (IFA) has also been widely tested in humans where it was shown to augment antibody responses greater than other adjuvants, such as alum, and to be well tolerated. Toxicity associated with the use of IFA has been controlled by the use of high grade oils and purified surfactants and clinical testing is ongoing to day. One potential limitation of IFA is that it does not augment the types of cellular immune responses that thought to be critical to the control of many viral infections and tumors. However, IFA can be mixed with or used in conjunction with other adjuvant-active compounds, such as saponins and cytokines. These mixed formulations or vaccine protocols have proved successful in animal testing and may soon be tested in clinical trials. Thus, the toxicity and potential limited adjuvant activity of IFA can be controlled or corrected making IFA a useful product in the vaccine industry.