Table 1.

Differentiation of primary hematopoietic precursor cells

Exp.	Virus	EPO antiserum	No. CFU-E	No. CFU-E (−uninfected control)	No. BFU-E	No. BFU-E (−uninfected control)
A	Uninfected	−	5  ±  1	0	5  ±  2	0
		+	0	0	0	0
	Uninfected + EPO	−	71  ±  10	66	8  ±  3	3
		+	7  ±  4	7	2  ±  1	2
	cEPOR	−	141  ±  23	136	42  ±  2	37
		+	79  ±  11	79	30  ±  7	30
	cEPOR (1–255)	−	20  ±  8	15	15  ±  3	10
		+	9  ±  2	9	2  ±  2	2
	cEPOR/G-CSFR	−	97  ±  9	92	17  ±  3	12
		+	76  ±  22	76	9  ±  1	9
	cEPOR/GHR	−	79  ±  6	74	13  ±  2	8
		+	63  ±  12	63	8  ±  2	8
B	Uninfected	−	4  ±  2	0	9  ±  6	0
		+	0	0	2  ±  1	0
	cEPOR	−	67  ±  12	63	28  ±  5	19
		+	39  ±  9	39	12  ±  3	10
	cEPOR/Mpl	−	33  ±  10	29	8  ±  2	0
		+	5  ±  2	5	1  ±  0.4	0

Embryonic day 13 fetal liver cells were prepared and infected. To each dish, either normal rabbit IgG (0.5 μg/ml) or rabbit polyclonal antierythropoietin antibody (+, 5 μg/ml) were added. In one condition (+EPO) human EPO was added to the cultures at 0.3 unit/ml. CFU-E numbers were determined at day 2 of culture; BFU-E numbers were determined at day 7. Data are expressed as mean ± SD (n = 4). Experiments A and B were performed on separate days.