M. Gursel et G. Gregoriadis, INTERLEUKIN-15 ACTS AS AN IMMUNOLOGICAL CO-ADJUVANT FOR LIPOSOMAL ANTIGEN IN-VIVO, Immunology letters, 55(3), 1997, pp. 161-165
The recently discovered interleukin-15 (IL-15) is known to bind to the
receptor of interleukin-2 (IL-2) and to share several of the latter's
immunological properties. In the present study, the first to our know
ledge on IL-15 behaviour in vivo, we examined the possibility that IL-
15 also shares the ability of IL-2 to enhance the immunological adjuva
nt property of liposomes by acting as a co-adjuvant. The cytokine and
a model antigen (tetanus toroid) were either co-entrapped by the dehyd
ration rehydration method into, or covalently co-linked by diazotizati
on to the surface of the same liposomes, or entrapped in different lip
osome populations. Intramuscular immunization of CD-1 mice with a vari
ety of IL-15 and toroid formulations revealed that IL-15 augments anti
-toroid IgG (IgG(1,) IgG(2,) IgG(2b)) responses well above (up to ten-
fold) those achieved with liposomal toroid alone (or with a mixture of
free IL-15 and toroid) when the cytokine and the antigen are associat
ed with the same vesicles but not when in different vesicle population
s that were mixed before injection. Higher responses were observed for
all three subclasses studied only with liposomes where IL-15 and anti
gen were accommodated on their surface. (C) 1997 Elsevier Science B.V.