Colorimetric B cell proliferation assay based on alkaline phosphatase activity. Selective measurement of B cell proliferation in the presence of other cell types.

In this study we show that a rapid colorimetric determination of alkaline phosphatase (APase) activity can be used in conjunction with a multiwell scanning photometer to quantitatively measure lymphokine-dependent B cell proliferation. Despite the fact that only activated but not resting B cells exhibit APase activity, i.e., that APase expression in B cells is variable, the results obtained by monitoring the enzyme activity were very similar to those obtained by measuring thymidine incorporation in two murine B cell systems. With regard to a potential application to the screening of the effects of hybridoma supernatants on B cells, it is relevant that HAT medium has practically no influence on the colorimetric B cell proliferation assay. Another advantage of the method is that since T cells and macrophages lack APase activity, one can detect the proliferation of B cells even in the presence of a high number of such cells, for example, in studying a T cell-dependent response.