Hemolytic complement measurement in eleven species of nonhuman primates

A microtiter system was used to measure hemolytic complement levels in serum from eleven nonhuman primate species. The species studied were $\text{Macaca mulatta}$ (rhesus macaque), $\text{Macaca radiata}$ (bonnet macaque), $\text{Macaca nemestrina}$ (pig-tailed macaque), $\text{Macaca fascicularis}$ (crab-eating macaque), $\text{Macaca speciosa}$ (stumptailed macaque), $\text{Papio cynocephalus}$ (yellow baboon), $\text{Papio anubis}$ (olive baboon), $\text{Cercopithecus aethiops}$ (African green monkey), $\text{Aotus trivirgatus}$ (owl monkey), $\text{Ateles fusceps robustus}$ (spider monkey), and $\text{Galago crassicaudatus panganiensis}$ (thick-tailed galago).The optimal hemolytic complement titer of the various nonhuman primate species was found to vary with different species sources of erythrocytes and anti-erythrocyte reagents used in the assay. No single erythrocyte and anti-erythrocyte test reagent produced optimal titers for all of the primate species examined. Sera from several species was found to have high spontaneous lytic activity towards non-sensitized sheep erythrocytes which for six species ($\text{M. mulatta, M. radiata, M. speciosa, P. cynocephalus, P. anubis}$ and $\text{A. trivirgatus}$) was equal to the titer for antibody sensitized erythrocytes. Evidence of alternate pathway complement activation as a possible reason for the high titer of lytic activity towards unsensitized erythrocytes could not be demonstrated for any nonhuman primate species. In one species, $\text{M. mulatta}$, the sensitizing activity of normal serum for sheep erythrocytes was shown to be in the IgM containing fraction obtained with gel filtration and to be absorbed by boiled sheep erythrocyte stroma which contains Forssman antigen.