Combined heterozygous loss of Ebf1 and Pax5 results in development of disease and increased mortality. (A) Kaplan-Meier curves describing the 40-week survival of Wt, Ebf1^+/−, Pax5^+/−, and Pax5^+/−Ebf1^+/− mice. A drop in the curve describes unknown cause of death or development of swollen lymph nodes and subsequent euthanasia due to animal protection regulations. Mice euthanized for known reasons other than swollen lymph nodes are censored in the curves. Overall log-rank (Mantel-Cox test) P value is displayed. (B) Two enlarged, one inguinal and one brachial, lymph nodes from a Pax5^+/−Ebf1^+/− mouse. (C) Representative flow cytometric analysis of the cellular content of a representative lymph node (left) and the fraction of CD43^high or IgM⁺CD19⁺ cells in 4 analyzed nodes (right). (D) Quantitative RT-PCR data over gene expression analysis of sorted live cells in 4 analyzed lymph nodes. Sorted Pax5^+/−Ebf1^+/− BM pro-B cells and lymphoid primed multipotent progenitors were used as positive and negative controls. Expression levels are presented in relation to HPRT. Data represent 1 of 2 quantitative PCR experiments using triplicate PCR reactions for estimation of expression values. (E) Immunoglobulin heavy chain VDJ analysis from 3 of the analyzed live cell populations from nodes of mice displaying peripheral pro-B cell expansion. Cultured Wt pro-B cells were included to show the rearrangement signature of a polyclonal population.