Biosynthesis of glycosaminoglycans and proteoglycans by the lymph node

Previous studies of hyaluronan uptake and catabolism by lymph nodes indicat ed that the nodes might also add some HA of low molecular weight to the una bsorbed fraction that passes through from afferent to efferent lymph vessel s. The ability of lymph nodes to synthesise HA and proteoglycans was therefore examined (i) by perfusion of [H-3] acetate through an afferent lymph vesse l in vivo, and recovery of labeled products from the efferent lymph vessel and from the node after perfusion; and (ii) by tissue culture of lymph node s with [H-3] acetate. Perfusion of lymph nodes with [H-3] acetate in situ yielded: (a), in outflo wing lymph, small amounts of chondroitin/dermatan sulfate within the first hour which continued to be produced for up to 24 h; heparin in the second h our and HA in the third. In the nodes removed 17 to 19 h later, equal amoun ts of hyaluronan and chondroitin/dermatan sulfate and heparan sulfate prote oglycans were detected. In the tissue culture of lymph nodes: (1) HA, hepar in and proteoglycans of heparan sulfate and chondroitin/dermatan sulfate we re released into the medium but in the cell extract only heparan sulfate pr oteoglycan was detected; and (ii) molecular weight of the released hyaluron an ranged widely but was mostly less than 4-5x10(5) D; heparan sulfate prot eoglycan was 2.8x10(4) to 9.4x10(5) D; heparin 7.9x10(4) D and chondroitin sulfate 1.3x10(4) D, suggesting that the chondrotin sulfate were released f rom their proteoglycans core by enzymic degradation. It is concluded that lymph nodes can release HA, heparin, heparan sulfate a nd chondroitin/dermatan sulfate proteoglycans into efferent lymph but the a mount of hyaluronan is likely to be small without immune or other stimulati on and its molecular weight is lower than in other tissues.