[Phospholipid-deacylating activities of the mouse peritoneal macrophages during phagocytosis].
In the macrophages (M phi) obtained from mouse peritoneal exudates, five kinds of phospholipid-deacylating activities were detected using phosphatidylethanolamine (PE) and phosphatidylcholine (PC) labeled with [1-14C]oleic acid either in 1- or 2- position and 1- [1-14C]oleoyl-lysoPE, as substrates. Two types of phospholipipase A1 with pH optima of 4 to 6 and 8, respectively, and two types of phospholipase A2 activities with pH optima of 4 to 5 and 8, respectively, were identified. A detected lysophospholipase activity exhibited a broad pH optimum between 4 and 8. Both types of the phospholipase A1 and A2 of M phi hydrolyzed PE more than PC. Exogenously added Ca2+ did not increase the enzymatic activities. A comparison was made of three kinds of the M phi-phospholipid deacylating activities at pH8, after challenging the M phi with Mycobacterium lepraemurium, Escherichia coli, zymosan, or latex beads for 17 hours at 37 degrees C. The bacteria used to the phagocytosis were autoclaved. When the M phi were challenged with M. lepraemurium, the phospholipase A1, A2 and lysophospholipase activities were stimulated by about 160%, 150% and 140%, respectively. However, when challenged with E. coli, the phospholipase A1 activity remarkably decreased by about a third, although the phospholipase A2 activity was stimulated by about 150% that is similar to the challenge with M. lepraemurium. An inflammatory substance, zymosan seemed an effective inducer of the phospholipase A2, the enzymatic activity was remarkably stimulated by 260%, when challenged with 200 micrograms of zymosan. The increase in phospholipase A2 activity of the M phi pretreated with the bacteria or zymosan seems to result in an increase in the hydrolysis of arachidonic acid from the M phi-phospholipids to synthesize its inflammatory oxygenated metabolites. The lysophospholipase activity was not stimulated by the substances used to challenge the M phi, except for M. lepraemurium. No significant increase in three kinds of phospholipid-deacylating activities was observed after challenging the M phi with latex beads. It was considered from the above results that the M phi-phospholipid-deacylating activities at pH8 might be affected by sort of the ingested substances.
Matsuki
G
G
Kashiwabara
Y
Y
Nakagawa
H
H
D000818:Animals; D006863:Hydrogen-Ion Concentration; D008245:Lysophospholipase / Q000378:metabolism*; D008264:Macrophages / Q000201:enzymology* / Q000276:immunology; D051379:Mice; D009167:Mycobacterium lepraemurium / Q000276:immunology; D010529:Peritoneal Cavity / Q000166:cytology; D010587:Phagocytosis; D010741:Phospholipases A / Q000378:metabolism*; D054466:Phospholipases A1; D054467:Phospholipases A2
D010741:Phospholipases A; D054466:Phospholipases A1; D054467:Phospholipases A2; D008245:Lysophospholipase