Ly49A transgene interaction with H-2D^dprevents the infiltration of lymphocytes into nonlymphoid tissues in CTLA-4–deficient mice.

Dramatic infiltration of the nonlymphoid tissues was observed in the CTLA-4^−/− mice expressing the Ly49ATg in the absence of MHC class I-D^d, whereas there was no apparent T-cell infiltration in the Ly49ATg⁺ H-2D^dCTLA-4^−/− mice. Tissues were fixed in 10% buffered formalin and embedded in paraffin blocks. Sections were cut and stained with hematoxylin and eosin by conventional techniques. The representative data shown (of > 10 independent experiments) are tissue sections from liver (A) and pancreas (B) of animals 3.5 weeks of age. No overt lymphocytic infiltration into nonlymphoid tissue was observed in the Ly49ATg⁺ H-2D^dCTLA-4^−/− mice at 5 to 6 weeks of age (data not shown). Magnification, × 250.