Table 1.

Frequency of CD200⁺/CD200⁻EMT6 tumor clones in DLN of control mice of Fig. 1b

Source of DLN for tumor cloninga	EMT6 tumor clones			Mean (+SD) ODc415
	Clone frequencyb	CD200+c	CD200−c
EMT6 → wt BALB/c: at resection	1/1.1 × 106 (77 %:102)	7 ± 2	2 ± 1.6	0.313 ± 0.07
EMT6 → wt BALB/c: day 14 post-immunization	1/1.3 × 105 (74 %:131)	57 + 10	20 + 5	0.322 ± 0.07
EMT6 → wt BALB/c: day 28 post-immunization	1/5.6 × 104 (74 %:143)	1320 ± 135	464 ± 65	0.319 ± 0.08

Arithmetic mean (±SD) OD₄₁₅ for mCD200⁺ clones

^aTumor cells were cloned at limiting dilution as described in Fig. 1 (panel b) from DLN of mice injected with EMT6 tumor cells into the mammary fat pad, with tumors resected at 15 days, and mice receiving immunization with irradiated EMT6 2 days later. Mice were sacrificed for DLN harvest at 14 and 28 days post-immunization. Cells in limiting dilution plates were fixed at day 22 of culture and mCD200 expression assayed using rat anti-CD200 (see “Materials and methods” section). Data in row 1 shows results for DLN harvested from a separate group of EMT6-injected mice at the day of tumor resection

^b,cEstimated frequency of tumor cells in DLN. % of CD200⁺ clones and number of tumor clones counted in parentheses. CD200⁺ clones had an OD₄₁₅ > 3SD above the mean for control EMT6 carried in culture (CD200⁻); mean OD₄₁₅ for control wells was 0.11 ± 0.01. Values shown are the calculated number of cloneable cells per 10⁷ DLN cells