Two representative HD cases stained for HLA class I, TAP 1, and TAP 2. Biopsy material from HD case No. 4 expresses high levels of HLA class I (A), as well as TAP 1 (B) and TAP 2 (C). HD case No. 35 shows no detectable HLA class I (D), whereas TAP 1 (E) and TAP 2 (F) are expressed. Sections were counterstained with hematoxylin. T2 (TAP-negative cell line) and T1 (TAP-positive cell line) were used as controls for TAP 1 (G, I) and TAP 2 (H, J) staining. Original magnification × 672 (A, D) and × 420 (B, C, E-J).