Serum opsonization capacity, phagocytosis, and oxidative burst activity in neonatal foals in the intensive care unit.
BACKGROUND
Phagocytic activity of neonatal foals has been reported to be similar to that of adult horses, but serum opsonization capacity develops with age and may be further altered when opsonins are consumed during infection.


OBJECTIVE
Phagocytosis, oxidative burst activity, and serum opsonization capacity in neonatal foals admitted to an intensive care unit are reduced in comparison with control foals.


METHODS
Blood samples were collected from hospitalized neonatal foals and from control foals. Hospitalized foals were characterized as sick or septic on the basis of a sepsis score and received intravenous plasma transfusion.


METHODS
Phagocytosis, oxidative burst activity, and serum opsonization capacity were tested with flow cytometric analysis. Serum immunoglobulin and complement component 3 concentrations were determined with radial immunodiffusion. Serum amyloid A concentration was assayed with a commercially available solid-phase Sandwich ELISA Kit. Data were analyzed with nonparametric and regression methods. Alpha was set at P = .05.


RESULTS
Phagocytic functions of septic and sick foals were lower than control foals in the initial phase of the study (P = .01). Opsonization capacity was significantly higher when bacteria were opsonized with serum from septic (P = .029) and sick (P = .006) foals than from control foals on day 1. Opsonization capacity in septic foals was comparable with control foals on days 2 and 5. This effect was not accompanied by an increase in serum complement C3 or immunoglobulin G concentrations independently.


CONCLUSIONS
Our results suggest that phagocytic function could be decreased in hospitalized foals. The synergistic effect of opsonic elements provided by plasma transfusion may sustain opsonization capacity during sepsis.
Gardner
Rachel B
RB
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Nydam
Daryl V
DV
Luna
Jennifer A
JA
Bicalho
Marcela L S
ML
Matychak
Mary Beth
MB
Flaminio
M Julia B F
MJ
D000818:Animals; D000831:Animals, Newborn; D003176:Complement C3 / Q000378:metabolism; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000378:metabolism*; D006736:Horses; D007136:Immunoglobulins / Q000097:blood; D007362:Intensive Care Units; D008297:Male; D009895:Opsonin Proteins / Q000097:blood* / Q000378:metabolism; D010587:Phagocytosis; D016897:Respiratory Burst / Q000502:physiology*; D018805:Sepsis / Q000097:blood / Q000378:metabolism; D000685:Serum Amyloid A Protein / Q000378:metabolism
D003176:Complement C3; D007136:Immunoglobulins; D009895:Opsonin Proteins; D000685:Serum Amyloid A Protein