AGE-DEPENDENT AND SEX-DEPENDENT THYMIC ABNORMALITIES IN NZB X SJL F1-HYBRID MICE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (1) , 63-72
Abstract
The cellular organization of the thymus was investigated in 3 and 12 mo. old NZB .times. SJL F1 hybrid (NS) mice. Age-dependent alterations were demonstrated which differed strikingly according to the sex of the animals. In female mice, marked abnormalities of the thymus developed during aging. They consisted of a more or less pronounced hypertrophy accompanied by histological changes and modifications in the nature of the lymphocyte populations. Three types of qualitative changes were found at 12 mo. Cortical thymocytes were depleted as evidenced by histology, evaluation of peanut-agglutinin (PNA) binding and cell electrophoresis. Hyperplasia of the medullary lymphoid tissue occurred, probably reflecting the expansion of a population of mature T [thymus-derived] lymphocytes. This was further suggested by a rise (up to 60%) in the frequency of lymphocytes lacking both PNA receptor and B [bone marrow-derived] cell markers, an increased proportion (57%) of high electrophoretic mobility (EPM) lymphocytes and an augmentation of in vitro reactivities to phytohemagglutinin and, to a lesser extent, to concanavalin A. Significant numbers of B lymphocytes (up to 20%) also appeared as assessed by surface immunoglobulin and complement receptor detection which was accompanied by a vigorous responsiveness of thymus cells to lipopolysaccharide. None of these abnormalities was seen in the male mice. The thymus of NS males displayed a nearly normal age-related involution without major change in the proportions of its lymphocyte subpopulations. NS mice thus provides an interesting model of thymic disease influenced by sex-linked factors.