The Use of Spectral Analysis of Limiting Dilution for Investigating the Immune Response.

In this study we present a method for characterizing a spectrum of cells engaged in the humoral response by two parameters: the frequency and potential activity of antigen specific precursor cells. Spleen cells from mice immunized with ovalbumin were placed in microcultures in a limiting dilution assay. The values derived from positive cultures in an activity/cell number plot were compatible with Poisson distributions for distinct families of precursor cells displaying either positive or negative (suppressor-like) activities. Proposed limiting dilution spectral analysis combines the potentialities of the standard limiting dilution analysis with those provided by histograms of distribution according to the activity of positive cultures. This method opens new opportunities in detecting and characterizing distinct groups of limiting precursor cells.