Table 2.

CD4⁺ T cells from mL9-immunized mice mediate rejection of 6132A-PRO tumor cells in SCID mice

Exp.†	Tumor incidence* after 28 days
	No LNC transferred	CD4-negative LNC transferred	CD4-positive LNC‡ transferred
1	1/1	1/1	0/2
2	1/1	1/1	1§/2
3	1/1	1/1	0/2
Total	3/3	3/3	1/6¶

^*Mice that showed no visible or palpable tumor at 2 months after tumor cell inoculation were considered tumor-free. All six mice that received no LNC or CD4-negative LNC developed progressive tumors and had to be killed at 28 days. 

^†MACS-sorted LNC (3-4 × 10⁶) from mL9-immunized mice were adoptively transferred in SCID mice inoculated with 10⁵ 6132A-PRO tumor cells. 

^‡Three independent experiments were performed, and the purity of the respective CD4⁺ fractions as analyzed by flow cytometry was 91% CD4⁺. 

^§One mouse had a palpable nodule less than 3 mm in diameter that persisted for half a year and then slowly began to grow. 

^¶The Fisher Exact test for association of tumor incidence and type of cells transferred is statistically significant (P value = 0.015). Compared to the control mice or the CD4-negative LNC transferred group, both of which had to be killed at 28 days because of large tumor burdens (for typical growth curves consult Fig. 3), there was either complete rejection in the CD4-positive LNC receiving group (five mice) or complete arrest of growth for half a year (one mouse). For association of tumor rejection or arrest the P value was 0.002.