Effect of different components of the thymic stroma on the onset of AKR leukaemia.

Spontaneous leukaemia in AKR mice is characterized by an accumulation of thymocyte precursors prior to the onset of the disease. An insoluble thymic fraction (ITF), previously shown to provoke such an accumulation when injected to normal mice, caused a significant acceleration of death by leukaemia when given to pre-leukaemic AKR mice. Conversely, the injection of a soluble thymic factor (STF), believed to further differentiate thymocyte precursors, was shown to markedly delay the onset of leukaemia. These results are interpreted as reflecting the specific immune functions of T cells at different stages of maturation.