Boosting protein immunisation lowers Ab response

Shared Mac unknown at
Thu Mar 2 06:06:43 EST 2000

Hello to the denizens of bionet.immunology - I have a quick question.

Does anyone know if there are examples in the literature similar to the
following observation?

Following primary immunisation with a protein antigen (delivered using a
novel adjuvant) IgG Ab responses were observed that were significantly
higher than the response to Ag delivered in buffer.

Following a boost immunisation responses with adjuvant were even higher.

Following a second boost immunisation IgG Ab responses in the groups
receiving Ag in adjuvant had decreased compared to post-first boost and
were then not significantly different from the response in the groups
receving Ag in buffer.
Responses in the groups receiving buffer increased post-second boost so
this effect is not due to some problem with the Ag used in the second

Immunisations were s/c in mice.

Note also that at a low Ag dose Ab responses increased post-primary,
post-first boost and post-second boost for Ag delivered in adjuvant and

Thanks for any pointers - please reply to the group.

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