Cytoplasmic granules of basophilic leukocytes stain metachromatically and have been thought to contain sulfated glycosaminoglycans, presumably heparin. To test this hypothesis, we identified the [35S]glycosaminoglycans synthesized by guinea pig blood basophils in culture and in vivo. Basophils isolated from guinea pig blood were cultured for 20 hr in F12 medium—10% guinea pig serum containing sodium [35S]sulfate. Alternatively, basophils were purified from animals receiving repeated i.v. injections of sodium [35S]sulfate. Glycosaminoglycans were isolated from these basophils after pronase digestion and identified by the use of selective glycosaminoglycan-degrading enzymes. Approximately 55% of the [35S]glycosaminoglycans was degraded by chondroitinase AC, indicating the presence of chondroitin sulfate; an additional 30 to 35% could be degraded by chondroitinase ABC, indicating that dermatan sulfate was also present. The 15% glycosaminoglycan remaining after chondroitinase ABC digestion was degraded by purified heparitinase (heparanase), which has no effect on authentic heparin but degrades heparan sulfate. Thus, the glycosaminoglycan content of guinea pig basophils is a mixture of chondroitin sulfate, dermatan sulfate, and smaller amounts of heparan sulfate. No heparin was detected.

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