PTPRC and Autoimmunity: Given the increased number of Gr-1+ and B220+ cells in the BM of ngr1-/- mice together with the recent report that BAFF/BLyS, a factor important for B-cell survival (implicated in autoimmunity) can bind with high affinity to NgR1 to induce signal transduction [38], we assessed the granulocyte progenitor cell status from the BM of naïve ngr1-/- mice using a colony-forming assay.