Abstract: | Supernatants of blood lymphocytes from immunized guinea pigs after incubation with purified protein derivative (PPD) were fractionated on Sephadex G-75. The fractions were tested for activity to change the electrophoretic mobility of macrophages. Dependent on incubation time, three different regions of activity with an average molecular weight of 13 000, 40 000 and more than 100 000 were estimated. |