TY - JOUR
T1 - Production of TCII (vitamin B12 transport protein) by mouse mononuclear phagocytes
AU - Rachmilewitz, B.
AU - Rachmilewitz, M.
AU - Chaouat, M.
AU - Schlesinger, M.
PY - 1978
Y1 - 1978
N2 - The role of the mononuclear-macrophage system in the production of transcobalamin II (TCII), the vitamin B12 transport protein that delivers the vitamin to the tissues, was investigated in mice. Of all the organs examined for TCII content in unstimulated mice, highest TCII levels were found in the bone marrow. A considerable amount of TCII was present in peripheral blood monocytes. Small amounts of TCII were present in peritoneal exudate cells (PEC) and in the spleen. TCII was undetectable in the thymus and in lymph nodes. Following a single intraperitoneal injection of thioglycolate (TG), a significant increase of TCII concentration was observed in PEC, with a concomitant drop of TCII in the bone marrow. Cultures of PEC harvested from unstimulated and TG-stimulated mice synthesized and secreted considerable amounts of TCII into the medium. After a lag period of several hours the concentration of TCII in the culture medium increased constantly throughout the entire period of incubation (5-7 days). PEC from stimulated and unstimulated mice were separated into adherent and nonadherent populations. Only the adherent cells, i.e., the macrophages, were consistently found to produce TCII in vitro. These findings show that macrophages produce and secrete TCII. Macrophages, however, did not contain R binders (TCI and TCIII). The observation that concomitant with the rise of TCII in PEC following stimulation there was a marked fall of TCII in the bone marrow indicates that TCII is produced by precursors of mononuclear-macrophage cells in the bone marrow that migrate to the periphery.
AB - The role of the mononuclear-macrophage system in the production of transcobalamin II (TCII), the vitamin B12 transport protein that delivers the vitamin to the tissues, was investigated in mice. Of all the organs examined for TCII content in unstimulated mice, highest TCII levels were found in the bone marrow. A considerable amount of TCII was present in peripheral blood monocytes. Small amounts of TCII were present in peritoneal exudate cells (PEC) and in the spleen. TCII was undetectable in the thymus and in lymph nodes. Following a single intraperitoneal injection of thioglycolate (TG), a significant increase of TCII concentration was observed in PEC, with a concomitant drop of TCII in the bone marrow. Cultures of PEC harvested from unstimulated and TG-stimulated mice synthesized and secreted considerable amounts of TCII into the medium. After a lag period of several hours the concentration of TCII in the culture medium increased constantly throughout the entire period of incubation (5-7 days). PEC from stimulated and unstimulated mice were separated into adherent and nonadherent populations. Only the adherent cells, i.e., the macrophages, were consistently found to produce TCII in vitro. These findings show that macrophages produce and secrete TCII. Macrophages, however, did not contain R binders (TCI and TCIII). The observation that concomitant with the rise of TCII in PEC following stimulation there was a marked fall of TCII in the bone marrow indicates that TCII is produced by precursors of mononuclear-macrophage cells in the bone marrow that migrate to the periphery.
UR - http://www.scopus.com/inward/record.url?scp=0018071060&partnerID=8YFLogxK
U2 - 10.1182/blood.v52.6.1089.1089
DO - 10.1182/blood.v52.6.1089.1089
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 719165
AN - SCOPUS:0018071060
SN - 0006-4971
VL - 52
SP - 1089
EP - 1098
JO - Blood
JF - Blood
IS - 6
ER -