Table III.

Both tumor cells and host-derived APC present tumor-encoded Ag to CD4⁺ T cells in A/J→F₁ and B6→F₁ bone marrow chimeric mice^a

Expt. No.	Tumor Cells	Chimera	T Cell Depletion	T Cell: APC Ratio	IL-2 (pg/ml)
Expt. No.	Tumor Cells	Chimera	T Cell Depletion	T Cell: APC Ratio	A/J APC	C57BL/6 APC
1	SaI/A^b/HEL	A/J→F₁	—	10:1	55	357
				50:1	607	520
2	SaI/A^b/HEL	A/J→F₁	—	10:1	430	172
3	SaI/A^b/HEL	A/J→F₁	CD8	10:1	217	137
			CD4	10:1	7.3	4
4	SaI/A^k/HEL	B6→F₁	—	10:1	132	33
5	SaI/A^k/HEL	B6→F₁	CD8	10:1	0	197
			CD4	10:1	0	10.6

a A/J→F₁ or B6→F₁ bone marrow chimeric mice were challenged i.p. with SaI/A^b/HEL or SaI/A^k/HEL tumor cells, respectively, and splenic T cells were tested in vitro for IL-2 production in response to lysozyme plus I-A^b (C57BL/6) or I-A^k (A/J) APC, respectively. In some experiments, responding T cells were depleted for CD4⁺ or CD8⁺ T cells prior to assay.