The colorimetric assay for swine lymphocyte blastogenesis.

The colorimetric assay used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) was compared with the 3H-thymidine incorporation assay in swine lymphocyte blastogenesis induced by phytohemagglutinin-P (PHA) and concanavalin A (ConA). The correlation coefficients were 0.70 (n = 18, p < 0.01) in PHA and 0.82 (n = 18, p < 0.01) in ConA. The maximal responses were observed in cultures of 2.0 x 10(6) cells/ml with the final concentration of 2.5-10.0 micrograms/ml in PHA or 2.5-5.0 micrograms/ml in ConA for 72 hr. The stimulation index of peripheral blood lymphocytes from clinically healthy pigs aged 6 months were 1.77 +/- 0.10 (n = 10) in PHA and 1.96 +/- 0.18 (n = 10) in ConA, respectively.