Figure 1. CD73 expression is modulated among responding antigen-specific B lineage cells in response to immunization with T-dependent antigen.

Splenocytes and BM cells from B6 WT and control CD73KO mice were stained and analyzed by flow cytometry on the indicated days post i.p. immunization with NP-CGG in alum. Representative FACS histograms of CD73 expression are shown. 3 million events were collected per sample. (A) CD73 expression on splenic GC B cells from WT (solid line) or CD73 KO (shaded gray), identified as NIP⁺ kappa^lo CD38^low CD95^hi CD19⁺. For comparison, staining of WT kappa⁺ CD38^hi CD95^lo CD19⁺ cells, which are predominately naïve, is shown (dashed line). (Upper right) Percentage of CD73⁺ GC B cells as a function of time; each point represents an individual mouse. On days 72–77, GC B cells were gated as NIP⁺ kappa^lo CD95^hi CD19⁺ (without CD38 gating). (B) CD73 staining of PB/PC populations from the spleen and marrow of WT (solid line) and CD73KO (shaded gray) mice. Antigen specific splenic and BM PB/PC populations were identified as intracellular NIP₅BSA^hi surface B220⁻, and were a mixture of CD138^hi and CD138^lo cells. Similar results were seen when gated on IgG₁ ^hi.