HA-1 CTLs eradicate 3D microtumors mimicking primary tumors. H&E stainings reveal that microtumors (E-H medium controls) closely resemble the histologies of the corresponding primary tumors (A-D). BB65-RCC microtumors (E) show clear cells similar to a primary intermediately differentiated renal cell carcinoma (A). MDA-MB 231 microtumors (F) contain spindle-formed cells without orientation similar to a primary spindle cell carcinoma of the breast (B). 518A2 microtumors (G) show sheets of cells similar to a primary melanoma (C). MCF-7 microtumors (H) show acinus-like structures similar to a primary intraductal carcinoma (D). (E-H) HA-1 and H-Y CTLs destroy microtumors in a strictly mHag-specific manner, resulting in strongly reduced cellularity and cell debris. Bars in top 2 rows represent 100 μm; in bottom 2 rows, 50 μm.