Alternative and classical complement pathway activity in sera from colostrum-fed and colostrum-deprived neonatal pigs

Area of Science:

• Immunology
• Complement System Biology
• Neonatal Pig Physiology

Background:

• Neonatal pigs rely on passive immunity transfer via colostrum for immune system development.
• The complement system, comprising classical and alternative pathways, is crucial for innate immunity.
• Understanding complement pathway maturation in neonatal pigs is vital for disease resistance.

Purpose of the Study:

• To investigate the impact of different diets (porcine colostrum, bovine colostrum, synthetic diet) on complement (C) pathway activity in neonatal pigs.
• To determine if passive immunoglobulin absorption influences complement activity in newborn pigs.
• To elucidate the mechanisms driving complement pathway maturation in early life.

Main Methods:

• Haemolytic assays were employed to quantify classical and alternative complement pathway activities.
• Sera were collected from neonatal pigs raised on distinct dietary regimens.
• Immunoglobulin concentrations were measured to assess passive transfer.

Main Results:

• Colostrum-fed pigs showed increased immunoglobulin levels but not immediate, marked increases in complement activity.
• Both colostrum and synthetic diets led to gradual increases in classical and alternative complement pathway activities post-birth.
• Pigs fed colostrum exhibited greater increases in classical pathway activity (80-83%) compared to alternative pathway activity (12-13%) within 3 days.
• Pigs on a synthetic diet showed a 37% increase in classical C and a 24% increase in alternative C pathway activity.

Conclusions:

• Direct passive absorption of complement components has a minimal effect on functional complement activity in neonatal pigs.
• Colostrum may contain a factor that stimulates classical complement pathway activity.
• Humoral homeostatic mechanisms are the primary drivers for the observed increases in alternative and classical complement pathway activity in neonatal pigs.