EBV is detected in CD21⁺ B cells and in CD21⁻ T cells.(A) Photomicrographs of PBMCs stained by Immuno-FISH from patient 12. EBV is detected in B cells that are CD21⁺. (B) EBV is detected in CD3⁺ T cells that do not express CD21. EBV DNA was identified with the biotinylated FISH probe and streptavidin-conjugated Alexa 594, B cells using a combination of Alexa 647–conjugated anti-CD19 and anti-CD20 antibodies, T cells with Alexa 647–conjugated anti-CD3 antibody, and CD21 with Alexa 488–conjugated anti-CD21 antibody. Arrows indicate EBV-positive cells.