Effects of dialyzable leukocyte extracts with transfer factor activity on leukocyte migration in vitro. II. Separation and partial characterization of the components in DLE producing antigen-dependent and antigen-independent effects.

Previous studies have shown that DLEs with TFd activity produce both Ag-dependent specific effects (mediated by TFd) and Ag-independent effects on CMl as demonstrated in vitro by agarose LMl. In the present study, Sephadex G-25 gel filtration provided a simple method for separating the DLE components responsible for each effect into distinct fractions. Ag-independent LMl was produced predominantly by Sephadex fraction l, of MW greater than 5000. The active components, further purified on Bio-Gel P-10, were shown to be of MW 14,000 to 17,000 and to contain both polypeptide and ribonucliotide material. The Ag-independent LMl activity was stable to heating at 56 degrees C for 30 min but was partially destroyed at 80 degrees C for 30 min, and the responsible components were shown to act on PMN directly. Ag-independent ELM was produced exclusively by material in Sephadex G-25 fraction V and also acted directly on PMN, whereas the Ag-dependent specific LMl activity was found predominantly in fraction lVb and to a lesser extent in fraction V and could not be detected in a direct assay using only PMN. In addition, a new activity, designated "Ag-dependent ELM activity," which caused increased migration in the presence of Ag, was found in Sephadex fraction lVa. This latter activity might mask the Ag-dependent LMl activity in fraciton lVb. Bio-Gel P-2 chromatography separated the components producing Ag-dependent and Ag-independent effects in fraction V into two separate subfractions (Va and Vb) of MW 1100 to 2000 and less than 900. The activity in fraction lVb eluted at a position identical to that of the components in fraction Va on Bio-Gel P-2. Fractions Va and Vb contained both polypeptide and ribonucleotide material. The Ag-dependent specific LMl or TFd activity was found to be partially inactivated at 56 degrees C and completely destroyed at 80 degrees C. The components responsible for this TFd activity were further purified by HPLC on ODS resin. The TFd activity was mediated by components with retention times much greater than that of adenosine 3'-monophosphate. The active fraction was composed of both polypeptide and ribonucleotide material but did not contain deoxyribonucleotides.