Computer-assisted analysis of two-dimensional electrophoreses of human lymphoid cells

Two-dimensional electrophoresis in polyacrylamide gel provides a highly reproducible display of biosynthetically pulse-labeled cellular polypeptides, whose relative rates of synthesis can be judged from the relative spot densities they produce in fluorographic images of the electrophoreses. When experimental and control cell populations synthesize protein at differing rates, either the sample load per gel or the duration of exposure of gel to film may be adjusted to produce comparable experimental and control images with no alteration in the rank order of relative spot density. However, variation in the duration of pulse-labeling may significantly alter relative spot density. Film density saturation and nonlinear response to radiation may also alter relative spot density for polypeptides with very large or very small amounts of radioactivity. Stimulation of human peripheral blood lymphocytes with phytohemagglutinin alters the relative synthesis rates of certain polypeptides visualized on the gels. These can be quantitated by using an automated series of computer algorithms to analyze the images. Data from this analysis confirm statistically significant alterations in the relative densities produced by certain polypeptides. Various human lymphoblastoid cell lines may also be distinguished from each other by this technique.