Effect of P64k presensitization on its efficacy as an immunological carrier in mice

Recently, we have successfully employed the meningococcal P64k protein as a carrier for weak immunogens, Here, we study if presensitization with it ca n affect the murine antibody response against the hapten chemically coupled to P64k, We found that priming with 10 mug of P64k did not induce epitope- specific suppression against two out of three synthetic peptides, from vira l proteins, conjugated to this carrier. Depending on the anti-carrier antib ody titers elicited in the presensitized mice, we observed or not a suppres sed immune response against the third peptide. Presensitization with 100 mu g of P64k resulted in epitope-specific suppression when lower doses of conj ugate were administered. In summary, as described for other protein carrier s, P64k could induce epitope-specific suppression in mice, but it depends o n the hapten and the extent of carrier-specific immunity. Furthermore, this suppression can be overcome by increasing the amount of conjugate administ ered per dose in the presensitized animals. (C) 2001 Academic Press.