Because BBDP rats have a peripheral T cell lymphopenia that, in transgenic rescue experiments [29], has been proven to be due to its mutation in the Gimap5 gene [9], [10], [30], we hypothesized that the increased levels of ER stress proteins found in BBDP rat lymph node cells preparations (Fig. 1) would be associated specifically with the T cell compartment. Here, GIMAP5 is linked to lymphopenia.