From the Guidelines
Atypical lymphocytes in Epstein-Barr Virus (EBV) infections are typically T cells or Natural Killer (NK) cells.
Characteristics of Atypical Lymphocytes
- These atypical lymphocytes can exhibit large granular morphology and express specific surface markers such as CD16, CD56, and HLA-DR 1.
- They may also be oligoclonal or monoclonal, indicating a clonal expansion of these cells in response to EBV infection 1.
Association with EBV Infection
- The presence of these atypical lymphocytes is often associated with high IgG antibody titers against EBV VCA and EA 1, as well as elevated plasma EBV DNA 1.
- The expression of EBV latent proteins and RNAs, such as EBNA-1, EBERs, and LMPs, can also be detected in these cells 1.
Clinical Implications
- The appearance of these atypical lymphocytes can be a diagnostic feature of Chronic Active EBV (CAEBV) infection 1.
- However, it is essential to distinguish CAEBV from other EBV-associated lymphoproliferative disorders, such as T-cell or NK-cell lymphomas, which may require different management strategies 1.
From the Research
Lymphocytes in EBV Infections
- The lymphocytes that appear atypical in Epstein-Barr Virus (EBV) infections are primarily CD8+ T cells, with a small fraction of CD19+ B lymphocytes 2.
- Atypical lymphocytosis in EBV-positive cases is characterized by increases in CD3+/CD8+, CD3-/CD16/56+, CD3+/gammadelta+, CD8+/CD48-, CD8+/CD57-, CD8+/CD95+, CD4+/CCR5+ CD4+/CD7-, CD4+/CD43-, CD4+/CD48-, and CD4+/CD62L- subsets 3.
- EBV-positive cases are distinguished by increased numbers of absolute lymphocytes, atypical lymphocytes, CD8+ cells, NK cells, gammadelta T cells, CD8+/CD45RO+ cells, CD8+/CD57- cells, and CD8+/CD28+ cells compared to EBV-negative cases 3.
- The immunoblasts in EBV-infected lymphoid tissue are mostly CD20+ B cells with a post-germinal center immunophenotype, and can mimic lymphoma 4.
- Atypical lymphoid infiltrate with numerous MUM1+, CD10-, BCL-6- immunoblasts should raise suspicion of a reactive process like infectious mononucleosis 4.
- EBV-positive patients tend to have higher mean total WBC count, mean absolute lymphocyte count, and more frequent absolute lymphocytosis, absolute leukocytosis, and atypical lymphocytosis compared to EBV-negative patients 5.