The influence of thymus hormones on the NK cells activity.

The influence of thymus hormone preparations on NK cell activity was studied. The following preparations were used: crude extract from calf thymus (TFX), its fraction V (TFX V) and synthetic pentapeptide (TP-5) fragment of native hemopoietin. It was shown that all preparations under study activate NK cells in vitro. The weakest effect was observed in the case of TFX, while both TFX V and TP-5 showed equally good stimulatory properties. The obtained results are discussed. The weak effect of the crude TFX is probably caused by the fact that it contains only 15% of fraction V which is responsible for affinity to the immune system.