Prevalence of tri- and tetraantennary glycans of human alpha 1-acid glycoprotein in release of macrophage inhibitor of interleukin-1 activity.

Based on the affinity for concanavalin A (Con A), human alpha 1-acid glycoprotein (AGP) can be separated by chromatography on Con A-Sepharose gel into three variants: Con A unreactive AGP, Con A weakly reactive AGP, and Con A strongly reactive AGP. When exposed to native AGP or to its glycan variants, murine peritoneal macrophages released a factor that inhibited the interleukin-1 (IL-1) proliferative activity as measured in terms of the thymocyte comitogenic assay. Con A unreactive AGP, which contains tri- and tetraantennary glycans and no biantennae, proved to be more effective than Con A weakly and Con A strongly reactive variants, which contain one and two diantennary glycans, respectively. The inhibitory effect was not a function of the negative charge related to the sialyl residues and was not mediated by the mannosyl-fucosyl receptor.