Tissue specificity of BAFF-R H90-5 by immunohistochemistry. Frozen tissue sections were stained at a concentration of 10 μg/mL with BAFF-R H90 (top row) using various normal human tissue sections from 3 separate donors. Anti–beta-2-microglobulin (bottom row) was used as an internal tissue control. Lymphoid tissues such as the tonsil (positive control) showed distinct, strong staining within the mantle cuffs of the follicles. No nonlymphoid frozen tissues showed cross-reactivity with BAFF-R H90-5. Representative tissue sections are shown (original magnification ×40; except for tonsil shown at original magnifications ×40 and ×200).