title: Lymphocyte stimulation response in horses against phytohaemagglutinin and M protein of Streptococcus equi using whole blood.
abstract: Lymphocyte stimulation was observed in whole equine blood in the presence of phytohaemagglutinin and M protein extracted from a typical strain of Streptococcus equi. Blood samples were collected from several healthy horses and horse and pony foals and cultured in vitro with varying concentrations of phytohaemagglutinin and M protein for several days. Phytohaemagglutinin was found to induce lymphocyte stimulation in these animals. Highest mean stimulation indices in horse foals (49.3 +/- 24.4) and pony foals (54.7 +/- 32.0) were observed with 0.625 and 1.25 micrograms/mL phytohaemagglutinin, respectively, at either 72 or 96 hours of incubation. Significantly higher radioactive counts per minute in horse and pony foals were recorded in blood cultures incubated with 0.625 and 1.25 micrograms/mL phytohaemagglutinin. M protein induced a dose related stimulation response in adult horses. Maximum stimulation indices were observed against 125 micrograms/mL M protein at 96 hours. These stimulation indices were higher in adult horses (40.0 +/- 2.2) than observed in pony foals (14.4 +/- 15.7). Higher stimulation levels in adult horses indicated either nonspecific stimulation against M protein or previous exposure of these animals to S. equi.
mesh_terms: D000367:Age Factors; D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000494:pharmacology*; D002352:Carrier Proteins; D005260:Female; D006736:Horses / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology*; D013291:Streptococcus / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D010835:Phytohemagglutinins; C014689:streptococcal M protein