Jd. Lippolis et al., Pseudomonas exotoxin-mediated delivery of exogenous antigens to MHC class I and class II processing pathways, CELL IMMUN, 203(2), 2000, pp. 75-83
Peptides associated with class II MHC molecules are normally derived from e
xogenous proteins, whereas class I MHC molecules normally associate with pe
ptides from endogenous proteins. We have studied the ability of Pseudomonas
exotoxin A (PE) fusion proteins to deliver exogenously added antigen for p
resentation by both MHC class I and class II molecules. A MHC class II-rest
ricted antigen was fused to PE; this molecule was processed in a manner typ
ical for class II-associated antigens. However, a MHC class I-restricted pe
ptide fused to PE was processed by a mechanism independent of proteasomes.
Furthermore, we also found that the PE fusion protein was much more stable
in normal human plasma than the corresponding synthetic peptide. We believe
that effective delivery of an antigen to both the MHC class I and class II
pathways, in addition to the increased resistance to proteolysis in plasma
, will be important for immunization. (C) 2000 Academic Press.