The class-specific BCR tonic signal modulates lymphomagenesis in a transgenic model of c-myc transgene deregulation.

c-myc-3'RR mice developed Burkitt like lymphoma (IgM and IgD positive cells). We wished to study lymphomagenesis in mice carrying a modified B cell receptor with a higher level of tonic signal. The c-myc-3'RR transgene was introduced in a background with an IgH mutation that replaces IgM with IgA expression. Lymphoma arising in double mutant animals mostly carried the phenotype of activated cells, often expressing CD43, and in 10% of cases carrying a plasma cell phenotype. BCR tonic signal appears as a direct modulator of B cell malignancy phenotype. Burkitt lymphoma (BL) from 4 c-myc-3'RR mice, anaplastic (ANA) lymphoma from 4 c-myc-3'RR mice, CD43 negative lymphoma from 4 c-myc-IgA mice and CD43 positive lymphoma from 4 c-myc-IgA mice were investigated.