The production of heterologous antibodies to the human lymphokine: Leukocyte migration inhibitory factor (LIF)

Abstract

Human leukocyte migration inhibitory factor (LIF) produced by concanavalin A-stimulated lymphocytes was partially purified by Sephadex G-100 chromatography and immunosorption of protein contaminants. This material was injected into two rabbits, and the IgG-IgA fractions of the resulting antisera (anti-LIF) neutralized LIF induced by antigen (PPD tuberculin) with as equal efficiency as that of LIF induced by mitogen. Anti-LIF activity was neither removed by absorption with control supernatant or normal human serum nor was it suppressed by absorption with lymphocytes or lymphoblasts. On the other hand, antibodies against human lymphoid cells (ALG) did not reduce LIF activity, indicating the difference between anti-LIF and classical ALG. In support of this, anti-LIF, in contrast to ALG, was not cytotoxic to lymphocytes, and it did not inhibit spontaneous T-rosette formation with sheep erythrocytes. In crossed immunoelectrophoresis using a conventional proteinstaining technique, only three precipitates appeared. None of these contained LIF. However, a protein migrating in the prealbumin region appeared to be specific for lymphocyte stimulation. The nature and significance of this product is unknown.