Patel P J
Infect Immun. 1981 May;32(2):557-62. doi: 10.1128/iai.32.2.557-562.1981.
Age-related changes in resistance of mice to infection with Listeria monocytogenes were investigated. One-month-old mice exhibited the least resistance, and the resistance level increased over the first few months to reach a maximum by 8 months. Increase in age thereafter was accompanied by a slow but progressive decrease in resistance. Thus, 50% lethal doses for 1-, 8-, and 24-month-old mice were 10(4.2), 10(6.6), and 10(5.2), respectively. In spite of differences in resistance, the growth of Listeria in the organs of mice of different age groups was identical during the first 48 h of infection, regardless of the size of the inoculum. Moreover, both young (3- to 8-month-old) and old (22-month-old or older) mice inoculated with a small dose of Listeria were equally capable of inactivating the bacterial load in their spleens and livers within 8 to 10 days of infection. However, a difference in bacterial growth after day 2 of infection was observed when different age groups of mice were inoculated with a large dose of Listeria. These results suggest that the decreased capacity of aged mice to resist infection with Listeria is not due to deficiency in the innate mechanisms of antibacterial resistance, but instead is due to age-related decline in the capacity to acquire immunologically specific antibacterial immunity.
研究了小鼠对单核细胞增生李斯特菌感染的抵抗力随年龄的变化。1月龄小鼠的抵抗力最低，在最初几个月抵抗力水平逐渐升高，到8个月时达到最高。此后年龄增长伴随着抵抗力缓慢但持续的下降。因此，1月龄、8月龄和24月龄小鼠的半数致死剂量分别为10(4.2)、10(6.6)和10(5.2)。尽管抵抗力存在差异，但在感染的最初48小时内，不同年龄组小鼠器官中李斯特菌的生长情况相同，与接种量大小无关。此外，接种少量李斯特菌的年轻（3至8月龄）和年老（22月龄及以上）小鼠在感染后8至10天内均有同样的能力清除脾脏和肝脏中的细菌负荷。然而，当给不同年龄组的小鼠接种大量李斯特菌时，在感染第2天后观察到细菌生长存在差异。这些结果表明，老年小鼠抵抗李斯特菌感染能力下降并非由于先天性抗菌抵抗机制缺陷，而是由于获得免疫特异性抗菌免疫力的能力随年龄下降。
