title: A novel phosphocholine antigen protects both normal and X-linked immune deficient mice against Streptococcus pneumoniae. Comparison of the 6-O-phosphocholine hydroxyhexanoate-conjugate with other phosphocholine-containing vaccines.
abstract: A novel form of phosphocholine (PC), p-nitrophenyl-6-(O-phosphocholine)hydroxyhexanoate (EPC) coupled to keyhole limpet hemocyanin (KLH) has been compared with unencapsulated, avirulent Streptococcus pneumoniae (R36a) and with the traditional thymus-dependent form of PC, diazophenylphosphocholine (DPPC)-conjugated KLH for its vaccine potential against virulent S. pneumoniae. Immunization with any of these three PC-containing Ags protects normal mice against a lethal challenge with 10(4) S. pneumoniae, whereas only EPC-KLH provides total protection to Xid mice. DPPC-KLH and unencapsulated S. pneumoniae confer less than 40% protection in Xid mice. Passive transfer of a PC-specific hybridoma Ab made from EPC-KLH-immunized Xid mice also provided protection against lethal challenge with S. pneumoniae. Protective anti-PC Ab were capable of binding to the surface of virulent bacteria, whereas anti-PC Ab incapable of binding to the bacterial surface failed to protect. Furthermore, serum Ab from EPC-KLH immunized and protected mice bound to S. pneumoniae, whereas secondary Abs from DPPC-KLH- or R36a-immunized mice failed to bind to the bacteria. EPC-KLH is potentially a vaccine candidate for pneumococcal prophylaxis in settings of immune compromise.
authors.affiliation: Laboratory of Leukocyte Biology, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702.
authors.forename: R T
authors.initials: RT
authors.lastname: Fischer
authors.forename: D L
authors.initials: DL
authors.lastname: Longo
authors.forename: J J
authors.initials: JJ
authors.lastname: Kenny
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D001391:Azo Compounds / Q000276:immunology; D002208:Caproates / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006433:Hemocyanins / Q000276:immunology; D007153:Immunologic Deficiency Syndromes / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008817:Mice, Mutant Strains; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000276:immunology*; D011008:Pneumococcal Infections / Q000517:prevention & control*; D013296:Streptococcus pneumoniae / Q000276:immunology; D014960:X Chromosome
chemical_list: D000941:Antigens; D001391:Azo Compounds; D002208:Caproates; D010767:Phosphorylcholine; C088148:4-diazophenylphosphocholine; C088147:4-nitrophenyl-6-(O-phosphocholine)hydroxyhexanoate; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin