Age-associated increase in the expression of T-cell antigen receptor gamma-chain gene in conventional and germfree mice.
To determine whether environmental antigens such as intestinal microflora contribute to expansion of the T-cell repertoire, age-related changes in the expression level of T-cell antigen receptor genes encoding gamma, beta, and alpha chains were compared in the lymphoid tissues of conventional versus germfree mice. Irrespective of the conditions of maintenance, an age-associated increase in the expression of the gamma-chain gene was evident in the thymus and spleen. Both conventional and germfree old mice (age, 40 weeks) had a relatively high proportion of Thy1+ L3T4- Lyt2- cells but a reduced level of Thy1+ L3T4- Lyt2+ cells in the thymus compared with their counterparts (age 8 weeks). The thymic dysfunction but not the stimulation by intestinal microflora may contribute to this age-related increase in gamma-gene transcripts in these tissues. On the other hand, an age-associated increase in the expression of gamma RNA was not evident in the mesenteric lymph nodes of germfree mice, although a remarkable increase in the gamma-chain gene messages was detected in the lymph nodes of the aged conventional mice. These results suggest that the expression of gamma RNA in cells of gut-associated lymphoid tissue is partly influenced by intestinal microflora.
Yoshikai
Y
Y
Department of Immunology, Kyushu University, Fukuoka, Japan.
Matsuzaki
G
G
Kishihara
K
K
Nomoto
K
K
Yokokura
T
T
Nomoto
K
K
D000367:Age Factors; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D005856:Germ-Free Life; D007422:Intestines / Q000382:microbiology; D008198:Lymph Nodes / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013154:Spleen / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology
D000945:Antigens, Differentiation, T-Lymphocyte; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D016692:Receptors, Antigen, T-Cell, gamma-delta