Genetic and other effects on bacterial phagocytosis and killing by cultured peripheral blood monocytes of SLA-defined miniature pigs.

The influence of miniature swine major histocompatibility complex genes (SLA) upon phagocytic and bactericidal activities of peripheral blood monocytes against Salmonella typhimurium and Staphylococcus aureus was measured in vitro using cultured cells and bacterial/enzyme-dependent tetrazolium dye (MTT) reduction. Haplotype significantly influenced uptake and killing of each bacterium by monocytes of 4- and 8-week-old pigs. Cells from 4-week-old SLA ad and aa pigs were significantly better than all others at phagocytizing S. aureus and cells from dg and gg were poorest. Killing of S. aureus was highest at 4 weeks in SLA cd pigs and in dg and gg pigs at 8 weeks of age. Uptake and killing of S. typhimurium was highest in homozygous aa and cc haplotypes at 4 weeks and pigs with the c x d recombinant haplotype had highest uptake and killing of S. typhimurium at 8 weeks. Litter, but not sire, also influenced significantly the uptake and killing of S. aureus and S. typhimurium.