Enhancement of anti-Aeromonas salmonicida activity in Atlantic salmon (Salmo salar) macrophages by a mannose-binding lectin.
We investigated the effects of a calcium-dependent mannose-binding lectin isolated from the serum of Atlantic salmon on Aeromonas salmonicida viability and the anti-A. salmonicida activity of Atlantic salmon macrophages. In the absence of other factors, binding of this lectin at concentrations of 0.8, 4.0 and 20.0 ng ml(-1) to virulent A. salmonicida failed to significantly reduce (P> 0.05) cell viability. However, binding of the lectin to A. salmonicida did result in significant (P < or = 0.05) dose-dependent increases in phagocytosis, and bactericidal activity. Significant increases (P < or = 0.05) were also observed in phagocyte respiratory burst activity within the lectin concentration range of 4.0-20.0 ng ml(-1) but the stimulation was not dose dependent at these lectin concentrations. At the lowest lectin concentration tested (0.32 ng ml(-1)), a significant decrease (P < or = 0.05) in respiratory burst was observed. The structure and activity of this lectin are similar to that of mammalian mannose-binding lectins, which are known to play a pivotal role in innate immunity. The presence of this lectin may be an important defense mechanism against Gram-negative bacteria such as A. salmonicida.
Ottinger
C A
CA
Institute for Marine Biosciences, National Research Council Canada, Halifax, Nova Scotia.
Johnson
S C
SC
Ewart
K V
KV
Brown
L L
LL
Ross
N W
NW
D000333:Aeromonas / Q000254:growth & development*; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D037222:Collectins; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D037102:Lectins / Q000302:isolation & purification / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects / Q000502:physiology; D008264:Macrophages / Q000502:physiology*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D016897:Respiratory Burst / Q000187:drug effects / Q000502:physiology; D020317:Salmo salar / Q000097:blood*
D002352:Carrier Proteins; D037222:Collectins; D037102:Lectins