Differential effects of interferon-gamma on production of trypanosome-derived lymphocyte-triggering factor by Trypanosoma brucei gambiense and Trypanosoma brucei brucei.
Trypanosome-derived lymphocyte-triggering factor (TLTF) produced by Trypanosoma brucei brucei stimulates production of interferon-gamma (IFN-gamma) by CD8+ T cells, and it is reported that, in turn, IFN-gamma stimulates proliferation of T. b. brucei. We studied the role of TLTF in trypanosome proliferation using the Wellcome strain (WS) of Trypanosoma brucei gambiense and the ILtat 1.4 strain (IL) of T. b. brucei. Increase in the number of WS in infected rats is more rapid than IL and corresponds with comparatively higher levels of IFN-gamma. Production of IFN-gamma, as measured by protein and messenger RNA (mRNA) levels, was maintained by splenocytes from WS-infected rats, whereas levels decreased in IL-infected rats, accompanied by prolongation of infection. Expression of TLTF mRNA by in vitro-cultured WS was promoted in a dose-dependent fashion by addition of recombinant rat IFN-gamma at all concentrations tested. The addition of lower concentrations of IFN-gamma to cultured IL increased expression of TLTF mRNA, whereas, in contrast to WS, addition of 100 and 1,000 U/ml IFN-gamma decreased expression of TLTF by IL. These results show that unlike WS, elevated IFN-gamma concentrations lead to decreased TLTF production by IL. It is believed that decreased TLTF production in IL-infected rats leads to lowered IFN-gamma production, thereby slowing IL proliferation.
Nishimura
Kazuhiko
K
Division of Veterinary Science, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, 1-1, Gakuencho, Sakai, Osaka 599-8531, Japan. nisimura@vet.osakafu-u.ac.jp
Hamashita
Kanako
K
Okamoto
Yasuyuki
Y
Kawahara
Fumiya
F
Ihara
Hideshi
H
Kozaki
Shunji
S
Ohnishi
Yoshihiro
Y
Yamasaki
Shinji
S
D000818:Animals; D015870:Gene Expression / Q000187:drug effects; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D008297:Male; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014346:Trypanosoma brucei brucei / Q000187:drug effects* / Q000378:metabolism; D014347:Trypanosoma brucei gambiense / Q000187:drug effects* / Q000378:metabolism
D015800:Protozoan Proteins; D012333:RNA, Messenger; D007371:Interferon-gamma