Upregulation of FcRIα as determined by either flow cytometry or Western blotting of lysed cells (n = 6). (A) Example of Western blot data for cells at day 0 or day 7 after culture in the presence of 500 ng/mL of PS myeloma IgE; day 0 is the day that IgE was added to the cultures, which was generally after a 21-day culture to downregulate the receptors (basophils were obtained from leukapheresis packs). The number of total cells was held constant and the basophil purity was found to be the same for the two time points, averaging 45% ± 5% for the six experiments. (B) Average data for flow-cytometric measurements or Western blotting in terms of day 0 levels (n = 6) Western blot films were digitally imaged to determine the optical densities of the bands. The difference in the relative change as measured by flow cytometry or Western blotting was not statistically significant, but both measurements for day 7 were statistically different than day 0 (P = .022 and P = .010, respectively). Average starting fluorescence of the basophils was 52 ± 15 on day 0, corresponding to ≈60,000 receptors per basophil (see Materials and Methods).