Detection of a novel 40,000 MW excretory Toxoplasma gondii antigen by murine Th1 clone which induces toxoplasmacidal activity when exposed to infected macrophages.
To analyse target molecules of the CD4+ T-cell response to toxoplasma infection, a panel of Toxoplasma gondii-specific murine CD4+ T-cell clones has been established. Clone 3Tx15, belonging to the T helper 1 (Th1) subtype, abolished intracellular parasite growth when co-cultured with macrophages and live toxoplasma at a ratio of 2:2:1. This effect results from macrophage toxoplasmicidal activity induced upon parasite-dependent cellular interaction, an irrelevant Th1 clone failed in this three-party system. Clone 3Tx15 detects its corresponding antigen in the supernatant of infected cells and also reacts with a host cell-free preparation of T. gondii-excreted/secreted antigens. T-cell blot analysis of two-dimensionally separated toxoplasma lysate revealed a molecular weight of about 40,000 for the fractions stimulating clone 3Tx15. As checked in parallel enzyme-linked immunosorbent assay, the 40,000 MW T-cell antigen co-migrates with the excretory protein GRA4, the sole 40,000 MW T. gondii antigen hitherto known to be recognized by T lymphocytes. Nevertheless, neither recombinant GRA4 nor immunoaffinity-purified natural GRA4 was stimulatory for clone 3Tx15. Our findings thus demonstrate that Th1 clone 3Tx15 which induces toxoplasmicidal activity during antigenic interaction with infected macrophages defines a new 40,000 MW excretory T. gondii antigen.
Reichmann
G
G
Institute for Medical Microbiology and Virology, Heinrich-Heine-University, Düsseldorf, Germany.
Stachelhaus
S
S
Meisel
R
R
Mévélec
M N
MN
Dubremetz
J F
JF
Dlugonska
H
H
Fischer
H G
HG
D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis* / Q000737:chemistry; D001921:Brain / Q000276:immunology; D018929:Cell Culture Techniques; D002999:Clone Cells / Q000276:immunology; D017077:Culture Media, Conditioned; D005260:Female; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology*
D000953:Antigens, Protozoan; D017077:Culture Media, Conditioned; C079248:GRA4 protein, Toxoplasma gondii; D015800:Protozoan Proteins