Table 3.

TEL function is required for development of myeloid, mast cells, and megakaryocytes

A. TEL−/− ES cells do not contribute to bone marrow myelopoiesis
Chimera		Percent agouti		Macrophage/granulocyte colonies			Mast cells
genotype	age (week)			−G418	+G418		−G418	+G418
			>70	2240 ± 240		650 ± 5	+		+
	1		∼50	860 ± 20		370 ± 5	+		+
			<50	660 ± 80		205 ± 5	+		+
			<50	3120 ± 340		80 ± 0	+		+
+/−	3		<50	880 ± 105		280 ± 5	+		+
			>70	1285 ± 125		405 ± 65	+		+
	>8		>70	1400 ± 100		350 ± 5	+		+
			<70	260 ± 30		35 ± 5	+		+
			<70	665 ± 75		35 ± 10	+		+
			>70	875 ± 145		5 ± 5	+		−
			<50	2210 ± 390		0	+		−
−/−	1		<50	2270 ± 10		0	+		−
			<50	2100 ± 60		0	+		−
			<50	860 ± 10		0	+		−
	3		>50	1315 ± 95		0	+		−
			<50	1095 ± 45		0	+		−
			>70	1165 ± 165		0	+		−
	>8		>70	460 ± 40		0	+		−
			<70	500 ± 80		0	+		−
			<70	690 ± 60		0	+		−
B. Lack of megakaryocytic progenitors in the bone marrows of TEL−/− → wild-type chimeras
				Megakaryocyte colony no./1 × 106 bone marrow cells
−G418			+G418
	1		50	155 ± 45			60 ± 10
+/−			40	115 ± 25			35 ± 15
	6		80	165 ± 35			25 ± 3
			30	200 ± 30			10 ± 0
−/−	1		30	105 ± 5			0
	6		60	195 ± 15			0
			40	185 ± 10			0

(A) Bone marrow progenitor assays were performed using TEL/wild-type chimeras with various degrees of ES cell contribution. Bone marrow cells were cultured in methylcellulose supplemented with IL-1/IL-3/GM-CSF/G-CSF to obtain myeloid colonies indicated as no. of myeloid progenitors per 1 × 10⁶ bone marrow cells. To obtain homogeneous populations of mature mast cells, 2 × 10⁵ bone marrow cells/ml were cultured in DMEM supplemented with 10% FCS and IL-3 for 4 weeks. In the presence of G418 no viable cells were obtained from TEL^−/−/wild-type chimeras. Similarly, no viable cells were obtained from control wild-type C57BL/6 bone marrow cells upon G418 selection. (+) Mast cell growth; (−) no growth. 

(B) Progenitor assays were performed in the presence of kit-ligand (KL) and thrombopoietin. Pure and mixed (with erythroid) megakaryocytic colonies were enumerated on day 7. The identity of megakaryocytes was confirmed by May-Grunwald-Giemsa stain and histochemical staining for acetylcholinesterase activity.