The adjuvant activity of non-ionic surfactant vesicles (niosomes) on the BALB/c humoral response to bovine serum albumin.

The ability of non-ionic surfactant vesicles (NISV) to enhance antibody production against bovine serum albumin (BSA) was compared with Freund's complete adjuvant (FCA), in the BALB/c mouse. Two subcutaneous inoculations with NISV entrapped BSA induced antibody levels comparable to, and persisting as long as those produced by FCA by either the subcutaneous or intraperitoneal route of inoculation. Intraperitoneal inoculation of NISV did not generate as strong an antibody response. The adjuvant activity of NISV was wholly dependent on the BSA being entrapped within preformed vesicles; mixing free BSA with vesicles was not effective. Analysis of the anti-BSA IgG subclasses induced by NISV and FCA showed that NISV were generally better stimulators of IgG2a than was FCA, but poorer stimulators of IgG1. From this, we deduce that NISV are potentially better stimulators of the Th1 lymphocyte subset than is FCA and by inference, potent stimulators of cellular immunity. We believe that NISV may offer many advantages over other adjuvants in terms of immunological selectivity, low toxicity and stability.