Impact of CD38 Deficiency on B Cell Development in CD19-Deficient Mice

Physical interaction between the CD38 and CD19 proteins has been previously described. However, this association through the development of B lymphocytes has yet to be thoroughly investigated. To address this, we generated mice with a simultaneous absence of CD38 and CD19 proteins. Our results showed that Cd38 -/- Cd19 -/- mice had reduced survival. We suggest that the combined loss of CD38 and CD19 proteins results in normal B-cell maturation in the BM compared to WT mice. Nonetheless, these observations differ from those observed in Cd19 -/- mice. In DKO mice, a change in the proportion of the mature B-cell subset in BM was found in contrast to Cd38 -/- mice. On the periphery, reduced numbers of total splenocytes and total B cells were observed in DKO mice. In addition, some defects in splenic B-cell development were observed. For example, fewer absolute numbers of T1, T2, and mature B cells were found in comparison with WT mice. However, these subsets have no significant difference compared to Cd19 -/- mice. The MZ B-cell subset was almost depleted in Cd38-/-Cd19-/- mice, and a contrary effect was observed in FO B cells. Although not many differences were found in the proportions and absolute numbers during the different maturation stages of B cells between DKO and Cd19 -/- mice, a downward trend was observed in some of the steps during B-cell ontogeny. For this reason, the activation, proliferation, and immunoglobulin secretion, as well as the GC formation and MZ microenvironment in response to different stimuli, must be explored.