Adjuvant activity of the 163-171 peptide of human IL-1 beta administered through different routes.

The synthetic peptide VQGEESNDK, corresponding to the fragment 163-171 of human IL-1 beta, could potently enhance the primary and secondary response of mice immunized with SRBC, measured as the number of specific antibody-secreting cells in the spleen. This adjuvant activity was dose-dependent, being maximal when the nonapeptide was administered intraperitoneally (i.p.) or subcutaneously (s.c.) at 100 mg/kg or orally (p.os) at 33 mg/kg, reaching levels comparable to those attained by 20 ng/kg of hu rIL-1 beta given i.p. or s.c. A dose-dependent enhancement of the primary response to SRBC was also observed when IL-1 beta or its peptide fragment were injected intravenously (i.v.) together with the antigen, with a maximum activity at 10 micrograms/kg for the 163-171 peptide and 100 pg/kg for hu rIL-1 beta. Thus, the in vivo immunostimulatory activity of hu IL-1 beta depended on the administration route as follows: i.v. much greater than s.c. = i.p. much greater than p.os. Conversely, the adjuvant effect of the 163-171 peptide was: i.v. much greater than p.os greater than s.c. = i.p.