The analysis of limiting dilution assays conducted under non-saturating conditions

A form of mathematical analysis is presented which permits an extended analysis of limiting dilution assays under conditions in which either accessory factors, or cells or both are limiting. This is in contrast to the traditional form of analysis which permits only a single limiting parameter. Both make use of in vitro experiments in order to determine the number of antibody-producing cell precursors: the traditional form of analysis requires that all accessory cells or their factors be present in saturating concentrations; whereas in the analytic method employed here, not only B cells, but also accessory cells (macrophages) or their factors may be limiting. Analysis under non-saturating conditions permits greater elucidation of the mechanisms of intercellular interaction.