Some physicochemical properties of human leucocyte migration inhibitory factor (LIF)

Leucocyte migration inhibitory factor (LIF) obtained from human lymphocytes stimulated with concanavalin A was consistently and irreversibly blocked by the serine-esterase inhibitor phenyl-methyl sulphonylfuoride (PMSF). This effect was not due to fluoride ions, hydrolysis products of PMSF or to impurities. PMSF pulse treatment of human buffy coat cells did not affect cell migration under agarose. LIF was also irreversibly destroyed by treatment with L-cysteine and 2-mercapto-ethanol, suggesting that the molecule contains disulphide linkage groups decisive for its configuration and biological activity. Di-sodium EDTA completely inhibited LIF activity but only if present during the entire migration period. Removal of EDTA before LIF assay restored LIF activity. Leucotye migration was neighter influenced by L-cysteine nor by EDTA. LIF activity was slightly diminished after treatment at 56 degrees C for 1 h and completely lost at 80 degrees C for 1/2 h. Furthermore, LIF appeared rather stable when treated at pH values between 4 and 11. These findings suggest, but do not prove, an esterase or a protease nature of human LIF.

Affinity chromatography. A new technique for partial purification of human leucocyte migration inhibitory factor

Human leucocyte migration inhibitory factor (LIF) was subjected to affinity column chromatography on Sepharose-bound alpha-L-fucose. Following the addition of alpha-L-fucose to the running buffer adsorbed lymphokine was eluted almost quantitatively. A minimum of 70-fold purification of LIF was achieved.

Human leucocyte migration inhibition

Within the last decade a variety of techniques have been developed and used for the detection of cell-mediated immunity in man by means of leucocyte migration inhibition in vitro. A detailed description of the leucocyte migration capillary tube technique (LMCT) and the leucocyte migration agarose technique (LMAT) is given. The procedure for selecting and using the proper antigen concentration is described. A description is also given of the indirect LMAT and the technique for determination of concanavalin A-induced lymphocyte release of leucocyte migration inhibition factor. Applications of these techniques are mainly intended for the exploration of the immunobiology of lymphocytes and cellular interactions associated with the immune response and the investigation of clinical conditions in man, i.e. infectious diseases, autoimmune diseases, transplantation states, tumour diseases, contact hypersensitivity and immunological deficiency states. Selection and adaptation to suit the experimental aim is necessary to obtain optimal results with these techniques. Their usefulness may be increased through more extensive use of purified antigens and indirect assays.

Inhibition of human leukocyte migration inhibitory factor (LIF) by alpha-L-fucose

Peak leukocyte migration inhibitory activity was produced in vitro by human lymphocytes stimulated with concanavalin A and eluted from Sephadex G-100 gel columns in fractions containing molecules of mol. wt. 40,000-50,000 daltons. No activity was found in fractions containing molecules of mol. wt. 23,000 daltons which is the estimated size of the human macrophage migration inhibitory factor (MIF). In the present experiments migration inhibition was tested on human peripheral blood leukocytes migrating under agarose. Unconcentrated supernatant activity was reduced in a dose-related manner by alpha-L-fucose. At a concentration of 0.1 M alpha-L-fucose, the mediator activity was completely neutralized. The effect was reversible and specific for alpha-L-fucose. Concentrated supernatant activity, however, was only slightly reduced even in the presence of a higher concentration of sugar. The possible role of alpha-L-fucose as a part of a mediator receptor on the indicator cells is discussed.

An in vitro assay of leukocyte migration inhibitory activity from human lymphocytes stimulated with concanavalin A

Human venous blood lymphocytes, incubated for 22 h in serum-free culture medium with the plant mitogen concanavalin A (Con-A), elaborated products, which inhibited the migration of human buffy coat cells under agarose. Con-A was removed by applying the supernatants on small Sephadex G-100 columns. The leukocyte migration inhibitory activity (LMIA) was tested in a semi-quantitative modification of the indirect leukocyte migration agarose technique, which is described. Lymphokine activity, demonstrable as early as 9 h after activation of lymphocytes, was most pronounced after 22 h. Significant LMIA was demonstrated in 12 of 17 normal individuals at standard dilution of culture supernatants I/3. In 9 of the 12 experiments, assays of LMIA were carried out on stepwise diluted supernatants with detection of the greatest dilution with significant LMIA. In four experiments LMIA could only be detected after 3- to 12-fold concentrations of supernatants. Considerable individual variation was found, the amounts of LMIA varying by a factor of about 300. The reproducibility appeared to be quite high, but the factor stability of supernatants stored at -20 degrees C was surprisingly low.