Studies to date indicate that there may be a dose-sparing effect with the use of QS21. In animal studies, when QS21 has been employed as an adjuvant, it shifted both the dose response curve and allowed less antigen to elicit equivalent binding antibody titers to the rgp120 protein. There may also be an acceleration in the course of antibody response after both the first and the second immunizations. Although the final titers in response to vaccine given in both alum and QS21 appear similar after 3 doses in humans, this plateau may be reached more readily, and with a lower antigen dose, when using QS21 as an adjuvant. In addition, it has been established that using a lower dose of antigen may elicit an immune response which is characterized by lymphoproliferation and production of TH1-like cytokines such as INF-gamma, interleukin-2, interleukin-4, interleukin-5 and interleukin-10.