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Two migration inhibitory factors with different chromatographic behavior and isoelectric points
Journal of Immunology (Baltimore, Md. : 1950)
|June 1, 1977
Summary
Researchers identified two distinct forms of migration inhibitory factor (MIF) in guinea pigs. These MIF species differ in their isoelectric points and molecular weights, suggesting unique properties.
Area of Science:
- Immunology
- Protein Biochemistry
Background:
- Migration inhibitory factor (MIF) plays a role in immune responses.
- Previous studies suggested heterogeneity of MIF, but distinct species were not well-characterized.
Purpose of the Study:
- To identify and separate distinct molecular species of guinea pig migration inhibitory factor (MIF).
- To characterize the physicochemical properties of separated MIF species.
Main Methods:
- Stimulation of guinea pig lymph node cells with concanavalin A.
- Fractionation using Sephadex G-100 gel filtration, sucrose density gradient electrophoresis, and isoelectric focusing.
- Determination of isoelectric points and apparent molecular weights (m.w.) using Sephadex G-75 chromatography.
Main Results:
- Two distinct MIF species were successfully separated.
- pH 3-MIF: Isoelectric point (pI) of 3.0-4.5, apparent m.w. of 65,000 (Kd 0.05-0.12).
- pH 5-MIF: Isoelectric point (pI) of 5.0-5.5, apparent m.w. of 25,000-43,000 (Kd 0.15-0.23).
Conclusions:
- Guinea pig MIF exists in at least two distinct molecular forms.
- These species exhibit significant differences in isoelectric point and molecular size.
- Further research is needed to elucidate the functional implications of these MIF variants.