Recommended Alternatives to Freund’s Complete Adjuvant  

Adjuvants are added to many antigenic preparations to increase their immunogenicity and efficacy.  Freund's Complete Adjuvant (FCA) has historically been one of the better aduvants, but it typically causes significant tissue damage at the site of injection. Therefore, the IACUC discourages it use.  To promote proper consideration of alternatives to FCA, the following list of alternative adjuvants was compiled.   

• Freund's Incomplete Adjuvant (FIA) – Killed mycobacteria found in FCA are not included in FIA as this ingredient is the most inflammatory component of FCA. FIA is commonly used for boosting immunizations after an initial injection with FCA. It can also be used for the initial immunization, particularly when a strong antigen is used or moderate antibody levels are present. Efficacy is dependent upon vigorous mixing of the adjuvant and antigen until a stable emulsion has formed.  Numerous research product companies can supply FIA.
• ALUM - aluminum hydroxide; Al(OH)3. Aluminum hydroxide is a commonly used adjuvant in commercial products such as vaccines. It is especially good with strong antigens. Several sources of aluminum hydroxide are available. One commercially available source is Alhydrogel, Accurate Chemical & Scientific Co, Westbury, New York.
• TiterMax – This product is marketed as a replacement for Freund's complete adjuvant.  TiterMax is a stable, metabolizable water-in-oil adjuvant.  A single injection has shown to induce antibody titers greater than 2 injections of Freund's (Freund's complete adjuvant followed by Freund's incomplete adjuvant) according to its manufacturer. It is available from: CytRx Corporation, 6971 Peachtree Industrial Boulevard, Suite 103, Norcross, Georgia 30092 (800)-345-2987.
• Syntex Adjuvant Formulation (SAF) –This product was developed as an alternative to Freund's complete adjuvant. It is a stabilized oil-in-water emulsion. SAF activates complement by the alternate pathway and is said to selectively stimulate the humoral immune response to IgG2a in the mouse. It works better with proteins that have some hydrophobic aspect to promote their adherence to oil droplets. SAF is available from Chiron Corporation, Emeryville, California.
• Ribi Adjuvant System (RAS) - Ribi markets a variety of immunologic products. The primary product marketed as an alternative to Freund's complete adjuvant is an oil-in-water emulsion containing detoxified endotoxin (MPL) and mycobacterial cell wall components (TDW, CWS) in 2% squalene. This system is easier to use than Freund's complete adjuvant because of its lower viscosity.  It has very low toxicity such that it has been used in humans. It compares well with Freund's complete adjuvant.  Limited quantities are available from: Sigma-Aldrick as product M6536.
• Elvax 40W - This is an ethylene-vinyl acetate copolymer. While the production process is somewhat involved, the resulting immune response can equal that induced by Freund's complete adjuvant. Elvax 40W is available from DuPont Chemical Co., Wilmington, DE (800)-628-6208; (request Elvax customer representative)
• L-tyrosine – This co-precipitate of the amino acid and antigen has been shown to have excellent adjuvant properties, even surpassing Freund's complete adjuvant in some circumstances. While the co-precipitation procedure is not difficult, it requires some manipulation. The cost is negligible. Available from numerous chemical companies.
• Montanide - This manide-oleate compound has been reported to produce antibody levels equivalent to Freund's complete adjuvant. The product is available from ISA Seppic, Fairfield, NJ
• AdjuPrime - This is a carbohydrate polymer marketed as an alternative to Freund's complete adjuvant. Minimal information comparing its efficacy to other adjuvants is available. The carbohydrate is thought to create both a "depot" effect and an enhancement of the interaction between the antigen and antigen-presenting cells.
• Nitrocellulose-absorbed protein- Nitrocellulose-absorbed protein will give a desirable slow release of antigen over a period of 2 weeks to 2 months. Nitrocellulose is inert so it causes minimal inflammatory response.
• Gerbu adjuvant - This is an aqueous phase adjuvant that does not have a depot effect. Frequent boosting is needed to achieve a high-titer response.  It produces minimal inflammatory response. Gerbu adjuvant is available from C-C Biotech, Poway, California.
• Immune-stimulating complexes (ISCOMS) - ISCOMS are antigen-modified saponin/cholesterol micelles that form stable cage-like structures. Antigen quantities as low as 1 ug have elicited a significant immune response. ISCOMS can be successfully prepared in the laboratory.
• SuperCarrier - This and some similar products are convenient kits for coupling haptens, such as peptides and small proteins, to larger carrier molecules to enhance immunogenicity. The coupled proteins can be combined with other adjuvants. This product is available from Syntex Research 3401 Hillview Ave. P.O. Box 10850 Palo Alto, CA 94303