CD27 and angioimmunoblastic T-cell lymphoma: To better understand the functional phenotype of RBD-specific MBCs, we further compared RBD-specific resting MBCs (CD3-CD19+RBD+CD21+CD27+), RBD-specific activated MBCs (CD3-CD19+RBD+CD21-CD27+), RBD-specific atypical MBCs (CD3-D19+RBD+CD21-CD27-), and RBD-specific intermediate MBCs (CD3-CD19+RBD+CD21+CD27-) between AILD patients and HC groups.