The time course, localization and quantitation of T- and B-cell mitogen-driven apoptosis in vivo.
Apoptosis has very recently been visualized in situ in a mammalian thymus and spleen. We report here the first in situ visualization, localization and quantitation of the time course of mitogen-altered basal levels of apoptosis within the thymus and spleen of a vertebrate. Adult Xenopus leavis, South African clawed toads, were injected intraperitoneally with either the T-cell mitogen, Concanavalin (Con) A, or the B-cell mitogen, lipopolysaccharide (LPS). Controls, reflecting the basal level of apoptosis of both organs, were injected with isotonic phosphate-buffered saline for amphibians (APBS). ConA and LPS failed to enhance the nearly 2% apoptotic rate in the thymic cortex, which is made up largely of immature lymphocytes, but it did double the base level of 2% apoptosis in the mature lymphocytes of the medulla, particularly along the corticomedullary boundary. In the lymphoid splenic white pulp, the 2% basal level was exceeded slightly after ConA treatment, while the 6% basal lymphoid apoptotic rate in the red pulp was enhanced 7-fold in 12 h. LPS induced lymphocytic apoptosis in the partly erythropoietic red pulp of the spleen after 12 h but did not effect the white pulp. Extensive macrophage engulfment of apoptotic cells was apparent in both the thymus and the spleen.
Grant
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P
Department of Biology, Reed College, Portland, OR 97202-8299, USA.
Clothier
R H
RH
Johnson
R O
RO
Schott
S
S
Ruben
L N
LN
D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000276:immunology / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D013154:Spleen / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology*; D013997:Time Factors; D014982:Xenopus laevis
D008070:Lipopolysaccharides; D008934:Mitogens; D003208:Concanavalin A