Figure 7. Inflammatory stimulation accelerates emergence of MHC II^high monocytes and leukemic transformation.

A, Experimental design of chronic LPS stimulation experiment. Tet2^WT and Tet2^HR young mice (8-weeks-old) were injected with 16 doses of 35 ug of LPS (every three days).

B, Percentage of MHC II^high Monocytes in the peripheral blood of the indicated mice during the LPS treatment described in A.

C, Representative spleens of Tet2^WT and Tet2^HR treated with PBS or LPS with LPS treated Tet2^HR showing overt splenomegaly.

Experimental design. Bone marrow cells from Tet2^HR mice with transformed disease were transplanted into recipients sub-lethally irradiated CD45.1.

D, Spleen weights of of Tet2^WT and Tet2^HR treated with PBS and LPS

E, Hematoxylin & Eosin of spleen sections of the indicated mice. No to minimal involvement observed in Tet2^WT PBS and LPS treated samples. Chronic phase disease and signs of extramedullary MPN/MDS-MPN observed in Tet2^HR LPS treated samples.

F, Hemavet results showing red blood count (RBC) in Tet2^WT and Tet2^HR PBS and LPS treated mice

G, Percentage of MHC II^high Monocytes in the peripheral blood of the indicated mice 8 months following LPS treatment.

H, Percentage of LSK in bone marrow of old Tet2 ^+/+ or old Tet2^+/HR with transformed disease phenotype quantified by flow cytometry immunophenotyping.

I, Colony formation assay. Quantification of the number of colonies derived from serial plating of 10,000 unfractionated bone marrow cells collected from PBS and LPS treated Tet2 ^WT and Tet2 ^+/HR (n=3).

J, Tet2 mutant progenitors maintain a tight regulation through their hematopoietic differentiation during steady-state. However, inflammatory conditions such as aging and infections triggers the proliferation of the progenitor cells and their myeloid-bias differentiation into inflammatory monocytes. The uncontrolled inflammatory response, in part maintained by the Tet2^HR inflammatory monocyte contributes to the transformation of the progenitor cells and the sustained generation of leukemic inflammatory monocyte