Stabilization of normal variability in phytohemagglutinin-induced blastogenesis for improved quantitative...

Phytohemagglutinin-induced blastogenesis is used clinically as an estimate of immune competence but quantitative application is problematic since there is considerable variability. We sought to define for five normal subjects the degree of variability in repetitive testing using a constant culture methodology. A six-day growth response was determined as was the dose response to seven concentrations of PHA. Growth time to peak 3H-thymidine (3HTdR) incorporation was not constant and that PHA dose stimulating maximum 3HTdR incorporation varied by 2--16 fold for the retesting of subjects. A pooled dose response was not stablizing. There were statistical differences among subjects for PHA dose optimum (P less than 0.01), maximum evoked 3HTdR incorporation (P less than 0.05) and with varied plasma lots (P less than 0.001). However, for each individual subject, a stable maximum 3HTdR incorpoartion could be repetitively evoked by culturing in a constant plasma lot, stimulating by a broad range a PHA doses and by harvesting daily to assure peak growth.