Transcobalamin II level in peripheral blood monocytes—A biochemical marker in inflammatory diseases of the bowel

Transcobalamin II (TC-II) is the vitamin B12 binding protein which is responsible for delivering the vitamin to the tissues. Recent clinical and experimental observations provided evidence that cells of the mononuclear macrophage system produce TC-II. Since monocytosis and increased macrophage activity were reported in ulcerative colitis and Crohn's disease, we tested whether TC-II content in plasma and/or in peripheral blood monocytes (PBM) may serve as indicators of the disease activity. Peripheral blood monocytes were separated by Ficoll Hypaque sedimentation and TC-II levels were determined in plasma and in cell sonicates using the charged cellulose filter technique. Transcobalamin II levels [57CoB12 (cpm) 3 × 106cells] in PBM isolated before treatment from patients suffering from active ulcerative colitis, Crohn's disease of the bowel, and shigellosis were found to be three- to four-fold higher [1489 ± 191 (mean ± SE) (n = 19), 1328 ± 126 (n = 9), and 1640 ± 323 (n = 5), respectively] than that in PBM isolated from normal subjects [420 ± 42 (n = 20)(P < 0.01)]. Transcobalamin II levels in PBM decreased with clinical improvement. The transcobalamin II level in PBM isolated from patients with ulcerative colitis while receiving steroids or in remission maintained by sulfasalazine was only slightly elevated. Plasma TC-II levels were elevated only in one-third of the patients, and thus were not reliable enough to detect the increase both in TC-II production and the disease activity. These results indicate that TC-II in PBM of patients with inflammatory bowel diseases may serve as an indicator of the disease activity, and therefore further demonstrate the inflammatory response involved.