Schistosoma mansoni phosphoenolpyruvate carboxykinase, a novel egg antigen: immunological properties of the recombinant protein and identification of a T-cell epitope.
In schistosomiasis mansoni, hepatic granulomatous inflammation surrounding parasite eggs is mediated by CD4(+) T helper (Th) cells sensitized to schistosomal egg antigens (SEA). We previously showed that a prominent lymphoproliferative response of CD4(+) Th cells from schistosome-infected C57BL/6 (BL/6) mice was directed against a 62-kDa component of SEA. A partial amino acid sequence of the 62-kDa component was found to be identical with one present in the enzyme phosphoenolpyruvate carboxykinase (PEPCK). Based on this sequence, a cDNA clone containing the entire coding region of PEPCK was identified, and the full recombinant Schistosoma mansoni PEPCK (rSm-PEPCK) of 626 amino acids was purified from a prokaryotic expression system. rSm-PEPCK strongly stimulated a specific T-cell hybridoma, 4E6, as well as CD4(+) Th cells from SEA-immunized BL/6 mice and from infected BL/6, CBA, and BALB/c mice. In the infected mice, rSm-PEPCK elicited significant gamma interferon production as well as, to a lesser extent, production of interleukin-2 and -5. In BL/6 and BALB/c mice, the CD4(+) Th cell response to rSm-PEPCK was greater than that directed against the egg antigen Sm-p40; conversely, CBA mice responded better to Sm-p40 than to Sm-PEPCK. A 12-amino-acid region (residues 398 to 409: DKSKDPKAHPNS) was demonstrated to contain a T-cell epitope; synthetic peptides containing this epitope significantly stimulated specific hybridoma 4E6 and polyclonal CD4(+) Th cells. The identification and characterization of immunogenic egg components will contribute to the understanding and possible control of T-cell-mediated schistosomal disease.
Asahi
H
H
Department of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Osman
A
A
Cook
R M
RM
LoVerde
P T
PT
Stadecker
M J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D018604:Epitope Mapping; D000939:Epitopes; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains / Q000276:immunology; D008969:Molecular Sequence Data; D010063:Ovum / Q000201:enzymology / Q000276:immunology*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D012550:Schistosoma mansoni / Q000201:enzymology / Q000276:immunology*; D017386:Sequence Homology, Amino Acid; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000947:Antigens, Helminth; D016207:Cytokines; D000939:Epitopes; D011994:Recombinant Proteins; D010729:Phosphoenolpyruvate Carboxykinase (GTP)