Age-associated involution of cellular immune function. I. Accelerated decline of mitogen reactivity of spleen cells in adult thymectomized mice.
Autoimmune-susceptible (A/J and C57BL/6J) and nonautoimmune-susceptible (DBA/1J) strains of mice were adult thymectomized (aTx). Groups of mice treated by aTx, aTx and 330 rads (R), aTx and 650 R, and 330 R OR 650 R only, were compared to normal age-matched control (normal and sham Tx) mice. T cell functions were then followed as measured by in vitro spleen cell responsiveness to the T cell mitogens phytohemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) in a long-term study. A decline in spleen cell responsiveness with natural aging up to 18 months of age was seen to PHA in all three strains and to SEB in A/J and C57BL/J mice. Adult Tx alone was followed by an accelerated decline in spleen cell responsiveness to PHA and SEB in all three strains of mice. Irradiation combined with aTx-reduced spleen cell responsiveness to SEB in A/J and DBA/1J mice. Irradiation with or without aTx diminished the bone marrow stem cell pool as measured by exogenous colony-forming units, and the hematocrit of all three strains of mice. Thus, the natural decline in cellular immunity with aging was accelerated by aTx in both autoimmune-susceptible and non-autoimmune-susceptible strains of mice. These results emphasize that physiologic thymic function(s) must continue throughout life in order to maintain T cell function.
D000375:Aging; D000818:Animals; D001854:Bone Marrow Cells; D004768:Enterotoxins / Q000494:pharmacology; D006400:Hematocrit; D007111:Immunity, Cellular; D037102:Lectins / Q000494:pharmacology; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D008214:Lymphocytes; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008934:Mitogens / Q000494:pharmacology*; D013154:Spleen / Q000276:immunology; D013934:Thymectomy; D013997:Time Factors
D004768:Enterotoxins; D037102:Lectins; D008934:Mitogens