β₂ microglobulin stimulation of mononuclear leukocytes
Genis, Carol A.
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Chemotaxis is a phenomenon in which cells move in the direction of a chemical gradient. Both neutrophils and macrophages exhibit chemotactic behavior in response to molecules released during inflammation. Activated lymphocytes produce the peptides lymphocyte derived chemotactic factor (LDCF) and β₂ microglobulin (β₂m)- Both LDCF and β₂m have similar molecular weight and isoelectric point. The similarity between the physicochemical characteristics of these two peptides and their mode of production led us to believe that β₂m may be chemotactic. The purpose of this study was twofold: (1) to determine if β₂m is chemotactic for mononuclear cells and (2) to determine if β₂m and one of the LDCFs are identical. Two assays for monocyte stimulation were used in this study: chemotaxis and superoxide anion release. The chemotaxis assay indicates that β₂m is capable of stimulating a monocyte chemotaxis response at a concentration of 16-25 μg/ml. The superoxide anion release assay also showed monocyte stimulation by β₂m at a concentration of 16 μg/ml. This indicates that β₂m may function as a lymphocyte derived chemotactic factor. However, considerable variation in the positive and negative controls was experienced in both the chemotaxis assay and the superoxide anion release assay, making a clear conclusion difficult. The LDCF produced in our laboratory proved to be heat stable, nondialyzable, and to retain activity after freezing and thawing. Molecular sieve chromatography yielded chemotactic activity in the 15-20,000 MW region. Activity was so dilute after column chromatography that it prevented further characterization of the LDCF preparation to determine if β₂m and LDCF were identical.