Plasma proteins in human cortical bone: enrichment of alpha 2 HS-glycoprotein, alpha 1 acid-glycoprotein, and IgE.

Human cortical bones were extracted with EDTA, and the residue after EDTA extraction was digested with bacterial collagenase. Ten plasma proteins were identified and quantitated in the EDTA extracts. Three of them--IgE, IgD, and alpha 1acid-glycoprotein--had not previously been described in bone or dentine. Five plasma proteins identified in collagenase digests are albumin, IgG, IgA, IgE, and alpha 1acid-glycoprotein. IgE, alpha 1acid-glycoprotein, and alpha 2HS-glycoprotein were found to be concentrated in the bone more than other plasma proteins by factors between 11 and 525. The identification of plasma proteins was facilitated by the addition of polyethylene glycol in agarose gel. The presence of plasma proteins both in EDTA extracts and in collagenase digests suggests their structural role in bone.