Quantitation of mu mRNA by in situ hybridization reveals a correlation between B-maturation associated antigens and IgM gene activation in acute lymphatic leukemias.

Acute lymphatic leukemias, expressing the common acute leukemia antigen were investigated for expression of early T- and B-cell associated markers and the activation of the gene for the heavy chain of the immunoglobulin M. The gene activation as determined by quantification of the mu mRNA with a fluorochrome labeled gene probe in situ in individual cells showed a wide spectrum of positivity which was correlated to increasing expression of B-maturation markers. There was also a correlation between the amount of cellular immunoglobulin as determined by immunofluorimetry. Quantitation of mRNA in individual cells may allow to determine the degree of gene activation in antigenically defined individual cells and may thus contribute a new tool for classification of normal and malignant cells.