Effect of fetal thymic extract on maturation of precursor lymphocytes from cancer patients with various stages.

Thymus humoral factor seems to have an ability of differentiating the precursor T cells (PTC) into cells bearing T-cell (thymus-dependent lymphocyte) characteristics. Human fetal thymic extract (hFTE) was examined for in vitro effect on the concanavalin A (Con A) responsiveness of peripheral blood lymphocytes in 28 patients with uterine cervical cancer and 9 healthy volunteers. The result was expressed as percentage increase of Con A response of the hFTE-treated group to that of the nontreated group. The effect of hFTE was found to be pronounced in patients in Stages 0 and I, in spite of the small difference in T-cell count in unit volume of peripheral blood. Meanwhile, the effect of hFTE was no longer observed in patients with advanced cancer (Stages III and IV). The present study has suggested that some of PTC, which are prevented from differentiating into mature T cells in vivo due to presumably depressed thymic hormone production, accumulates in peripheral blood of patients with early cancer. And it was also suggested that decrease of both PTC and T-cell count in patients with advanced cancer is due to general immunodeficiency.