CD21 is a cell surface-associated protein expressed in the follicular dendritic cells (FDCs) of lymphoid tissues, and in tumors derived from FDCs. Disruption of CD21-positive FDC meshworks can be seen in a variety of lymphomas. CD21 is also expressed by a significant subset of B cells, and is the receptor for Epstein-Barr virus.
Subcellular Localization: Membranous
CPT Code(s): 88342 or 88341 (reference only; CPTs may vary)
Turnaround Time: Within 1-2 business days of receipt
Schedule: Monday - Friday
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR -
• 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm