CD4(+) alpha betaT cells from either normal C57BL/6 (B6) or MHC-II-deficien
t (A alpha (-/-) or A beta (-/-)) B6 donor mice engrafted into congenic imm
unodeficient RAG1(-/-) B6 hosts induced an aggressive inflammatory bowel di
sease (IBD), Furthermore, CD4+ T cells from CDld(-/-) knockout (KO) B6 dono
r mice but not those from MHC-I-/- (homozygous transgenic mice deficient fo
r beta (2)-micro-globulin) KO B6 mice induced a colitis in RAG(-/-) hosts,
Abundant numbers of in vivo activated (CD69(high)CD44(high)CD28(high)) NK1(
+) and NK1(-) CD4(+) T cells were isolated from the inflamed colonic lamina
propria (cLP) of transplanted mice with LED that produced large amounts of
TNF-alpha and IFN-gamma but low amounts of IL-4 and IL-10, IBD-associated
cLP Th1 CD4(+) T cell populations were polyclonal and MHC-II-restricted whe
n derived from normal B6 donor mice, but oligoclonal and apparently MHC-I-r
estricted when derived from MHC-LI-deficient (A alpha (-/-) or A beta (-/-)
) B6 donor mice. cLP CD4(+) T cell populations from homozygous transgenic m
ice deficient for beta (2)-microglobulin KO B6 donor mice engrafted into RA
G(-/-) hosts were Th2 and MHC-II restricted, These data indicate that MHC-I
I-dependent as well as MHC-II-independent CD4(+) T cells can induce a sever
e and lethal PBD in congenic, immunodeficient hosts, but that the former ne
ed the latter to express its IBD-inducing potential.