Correlation between mature and immature thymocytes. Immature thymocyte potentiating factor (IMPF) produced by mature thymocytes.

Low-dense mature thymocytes (MT) and high-dense immature thymocytes (IMT) were investigated. Immature thymocyte-potentiating factor (IMPF) was found in the supernatant from MT stimulated by Con A. On the other hand, suppressing activity was present in the supernatant from the unstimulated IMT. IMPF was different from Con A itself. Sephadex G-100 gel chromatography of IMPF revealed that the activity was recovered at the position between bovine serum albumin and ovalbumin.