In the low leukemic strains of mice, a subpopulation of thymocytes located in the medullary area are highly immunocompetent cells. In AKR mice, nearly 75% develop lymphomas which are initiated with the thymic medullary region. The experiments were carried out to investigate the immunocompetence of AKR thymic medullary cells and cell mediated cytotoxic function, both in normal and neonatally thymectomized (Tx) mice. Hydrocortisone resistant thymus cells obtained from 2 to 3 mth old AKR mice had a significantly higher capacity to induce graft versus host reaction (GVHR) and an increased stimulation with mitogen (PHA) as measured by DNA synthesis in vitro. However, spleen cells from Tx animals had lower blast transformation by PHA and lower ability to induce GVHR. In contrast, spleen cells from immunized normal or Tx mice developed equal level of cytotoxic ability to release 51Cr from labeled target cells (DBA mastocytoma), and these immune cells were sensitive to anti theta AKR serum. The results suggest that: young adult AKR mice possess vigorous immunocompetent cells in the medullary area of the thymus, and lymphocytes cytotoxic to tumor cells are present at birth in AKR mice and do not, critically, require the postnatal influence of the thymus for maintenance and/or expansion. However, other subpopulation(s) of T cells involved in GVH or blast transformation by mitogens are either present at birth in lesser numbers or require the presence of the thymus for their maintenance and expansion. Both T cell subpopulations are not demonstrable in C3H Tx mice which develop 80 to 100% wasting disease and early death. The results presented explain the lack of wasting disease and the decreased incidence of leukemia in AKR Tx mice.
|Original language||English (US)|
|Pages (from-to)||No. 62|
|Journal||American Journal of Pathology|
|State||Published - Jan 1 1975|
ASJC Scopus subject areas
- Pathology and Forensic Medicine