Partial characterization of a murine lymph node activating factor released in cultures of H-2 incompatible lymphocytes.

By fractionation on Sephadex columns of the supernatants from mixed cultures of H-2 incompatible lymphocytes we succeeded in partially purifying a lymph node activating factor and in determining its molecular weight. The properties of the lymph node activating factor correspond to those of substances with 16 000 +/- 5 000 D, 65 000 +/- 10 000 D, and also substances with molecular weight higher than 200 000 D which we consider to be aggregates of the minor components. The lymph node activating factor resembles in its molecular weight and effects (in vitro lymph node activation) the products of activated lymphocytes described by other investigators.