The second is the interaction the adjuvant has with immune cells. Adjuvants may act as non-specific mediators of immune cell function by stimulating or modulating immune cells. Many of the adjuvants have the capacity to cause inflammation, tissue necrosis and pain in animals. A major charge to investigators is to minimize animal use and discomfort. Today several other adjuvants are available as alternatives and may be suitable for use in an investigator's experiments.
Adjuvant choice is also dependent upon selection of the species to be immunized.
Some studies are now published comparing antibody response after immunization with antigen complexed to different adjuvants. More work remains to be done and current information cannot be applied across the board to all antigen and adjuvant combinations. Adjuvant selection remains largely empirical. Antigens that are easily purified or available in large quantities may be good choices for starting with the least inflammatory adjuvants for immunization. Should antibody response not be suitable, a gradual increase in the inflammatory level of the adjuvant would then be warranted.