EVALUATION OF SEVERAL ADJUVANTS AS ALTERNATIVES TO THE USE OF FREUNDS-ADJUVANT IN RABBITS

In three experiments we evaluated several types of adjuvants as an alt ernative to Freund's adjuvant (FA). In the first experiment three adju vant preparations (a water-in-oil emulsion (Specol), a combination pre paration of monophosphoryl lipid A + trehalose dimycolate + cell wall skeleton and a non-ionic block polymer surfactant (TiterMax)) were eva luated. The adjuvants were combined with three different types of weak immunogenic antigens (synthetic peptide, glycolipid and particulate a ntigen) and administered following the intramuscular and subcutaneous route. The evaluation was based on clinical, pathological and immunolo gical parameters. The animals did not appear to be severely or chronic ally impaired by the experiment. After injection of the RIBI adjuvant, side effects of the same severity as with FA were induced, while low antibody titers were produced. TiterMax caused few side effects, while antibody responses were very low. In comparing Specol and FA, Specol had far fewer adverse effects than FA. However, Specol had immunostimu lating properties of the same level as FA. In the second experiment, t he effect of injected volume of FA on side effects and antibody titer was studied. Immunization of rabbits with a total of 0.5 mi FA at diff erent sites does not seem to increase the immune response when compare d with the immune response seen after injection of 0.5 mi FA at one si te. However side effects were seen in all the animals. In the third ex periment, the side effects following intradermal (i.d.) injection of t he adjuvants were studied. After i.d. injection of FA or RIBI, undesir able effects were found. No side effects occurred after i.d. injection of Specol or TiterMax. From the studies it is concluded that Specol i s an alternative to FA for hyperactivation of the immune response in r abbits.