The effect of calf thymus extract (TFX) on human and mouse hemopoiesis.

The in vitro and in vivo effects of calf thymus extract (TFX) on mouse and human hemopoiesis were studied. TFX enhanced the growth of mouse T- and B-lymphocyte colonies when given in vitro and in vivo; in humans it increased the low colony formation typical for some blood donors failing to act on lymphocytes of high responders. TFX markedly stimulated colony-stimulating factor (CSF) production by human leukocytes presumably influencing the interactions between monocytes and lymphocytes. Although TFX did not affect the proliferation and differentiation of myeloid progenitors of bone marrow and peripheral blood, it strongly stimulated myelopoiesis in mouse and human spleen.