Human helper T cell factor(s) (ThF). I. Partial purification and characterization.

T cells obtained from pleural effusion of patients with tuberculous pleurisy were stimulated in vitro with PPD. The culture supernatant was shown to be substituted for T cells in PWM-induced IgG production by human B cells. As many as 0.5 to 3 x 10(9) lymphocytes were obtained from 1 patient, and about 85% of them were E-rosette positive, making it possible to purify human helper T cell factor(s) (ThF). Helper activity was sensitive to heating at 70 degrees C for 5 min and treatment with trypsin. ThF did not have conventional Ig determinants and was recovered in the 50 to 67% ammonium sulfate fraction. The purification was done by successive DEAE-Sephadex and CM-Sephadex ion-exchange chromatography, Sephadex G-100 gel filtration, and isoelectric focusing. It was shown that ThF activity was eluted by gel filtration in the fraction with a m.w. of about 20,000. Isoelectric focusing of this fraction revealed that ThF activity distributed in the pl range of 6.5 to 8.0, whereas TCGF activity was focused in a single peak at pI of 6.5, indicating the existence of a helper factor without TCGF activity.