Expression and secretion of ficolin beta by porcine neutrophils.
Ficolins are collagenous lectins that bind N-acetylglucosamine (GlcNAc) as well as some bacterial surfaces, and may have opsonic and complement-activating functions. Ficolin alpha in porcine plasma binds Actinobacillus pleuropneumoniae serotype 5 (APP) in a GlcNAc-dependent manner. In the present study, we discovered that porcine neutrophils, but not platelets or mononuclear cells, contained a different ficolin that migrated as a 39-kDa band on SDS-PAGE and resembled a minor component of plasma ficolins that binds APP. However, neutrophil ficolins (pI range 6.4-7.4) were readily distinguished from plasma ficolin alpha (pI 5.2-5.8) by 2D PAGE. Neutrophil ficolin was consistent with ficolin beta by pI and peptide mass fingerprinting with matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Porcine neutrophils expressed ficolin beta, but not ficolin alpha, as determined by RT-PCR. Ficolin beta was present in the membrane and cytoplasmic fractions of nonactivated neutrophils, but the majority of ficolin beta was secreted upon activation with PMA. Ficolin alpha readily bound to intact APP, but ficolin beta did not under the same conditions. These studies demonstrate that neutrophils express ficolin beta and secrete it when activated; however, ficolin beta may have different binding functions than ficolin alpha.
Brooks
Andrew S
AS
Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Hammermueller
Jutta
J
DeLay
Josepha P
JP
Hayes
M Anthony
MA
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D037102:Lectins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009504:Neutrophils / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D000097604:Ficolins
D002352:Carrier Proteins; D037102:Lectins; D000097604:Ficolins