CD8+ T cells play disparate roles in the induction and the effector phases of murine experimental allergic conjunctivitis.
Although CD4+ Th2 cells clearly play an essential role in the development of experimental allergic diseases, the functions CD8+ T cells may have in these diseases have been investigated less extensively and remain controversial. Here, we investigated the roles of CD8+ T cells in the development of experimental allergic conjunctivitis (EC). EC was induced in CD8alpha-deficient (CD8KO) mice and wild-type (WT) mice by active immunization with short ragweed pollen (RW) followed by challenge with RW-containing eye drops. Alternatively, EC was induced by transferring RW-primed splenocytes followed by RW challenge. With regard to actively immunized mice, CD8KO mice showed significantly less severe eosinophil infiltration of the conjunctiva and lower total IgE levels, although the levels of the other Igs were equivalent between the two strains. Cytokine production by cultured splenocytes also did not differ, but the WT conjunctivas showed upregulated IL-5 and IL-6 expression and greater upregulation of IL-4 expression than the conjunctivas of CD8KO mice. Thus, CD8+ T cells may play a significant role during the induction phase by aiding IgE production and the generation of Th2 cytokines in the conjunctiva, thus promoting the development of EC. In contrast, splenocytes from CD8KO mice induced significantly more severe EC in WT mice than cells from WT mice. In addition, transfer of RW-primed splenocytes induced significantly more severe eosinophil infiltration in CD8KO recipient mice. Thus, CD8+ T cells promote the development of EC during the induction phase, but suppress it during the effector phase.
Fukushima
Atsuki
A
Department of Ophthalmology and Visual Science, Kochi Medical School, Japan. fukushima@med.kochi-u.ac.jp
Yamaguchi
Tomoko
T
Fukuda
Ken
K
Sumi
Tamaki
T
Kumagai
Naoki
N
Nishida
Teruo
T
Imai
Shosuke
S
Ueno
Hisayuki
H
D019264:Adoptive Transfer; D031164:Ambrosia; D000818:Animals; D016827:CD8 Antigens / Q000235:genetics; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018925:Chemokines / Q000276:immunology; D003228:Conjunctiva / Q000276:immunology; D003233:Conjunctivitis, Allergic / Q000139:chemically induced / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D004804:Eosinophils / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000166:cytology
D016827:CD8 Antigens; C431698:CD8alpha antigen; D018925:Chemokines; D016207:Cytokines