CD3-ε Overexpressed in Prothymocytes Acts as an Oncogene

Table 3 Expression of CD3-ε-derived transgenes induces transition from DN to DP thymocytes in young RAG-2^null and lck^null mice and lymphomagenesis in older mice

Thymus at 6–8 weeks
Genotype	Total no. of thymocytes^a × 10⁻⁶	% of Thymocytes^b		% of Mice with Lymphomas at 4–8 months^c
Genotype	Total no. of thymocytes^a × 10⁻⁶	Thy-1⁺ CD4⁻8⁻	Thy-1⁺ CD4⁺8⁺	% of Mice with Lymphomas at 4–8 months^c
RAG-2^null	5.6	100	0	0 (0/20)
RAG-2^null×tg26^+/+d	0.3	5 ± 3	0	0 (0/20)
RAG-2^null×tg26^+/−	1.4	45 ± 26	55 ± 26	50 (18/36)
RAG-2^null×tgΔ1^+/+e	3.6	19 ± 14	81 ± 14	n.d.
RAG-2^null×tgΔ1^+/−	9.4	5 ± 5	95 ± 5	25 (2/8)
lck ^null	13.4	34 ± 16	66 ± 16	0 (0/10)
lck^null×tg26^+/−	1.4	11 ± 10	82 ± 10	67 (6/9)
lck^null×tg26^+/+d	0.8	5 ± 3	0	0 (0/4)

^aTotal number of thymocytes is the average of numbers from 4 to 10 mice.
^bPhenotype of the thymocytes was determined by three-color flow cytometry. The conversion from DN to DP was probably going through a CD8 SP stage, as 5 to 35% of thymocytes were CD4^loCD8⁺ cells in approximately 30% of the mice. For simplicity, these cells were categorized as DP cells in this table.
^cThe frequency was determined as described in Materials and Methods. The number of mice that died of lymphomas and the total number of mice monitored are indicated in parentheses, n.d., not determined.
^dIn RAG^null×tg26^{+ +} and lck^null × tg26^+/+ mice, the majority of thymocytes were Thy-l⁻ B cells (29).
^etgΔ1 = tgεΔ1-2966H.

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