Immunological features of the patient. (A) Lymphocytes subpopulations. Serum immunoglobulin levels. (B) Liver histopathology. Immunohistochemistry was performed on fixed tissues with a peroxidase-based method (Dako). Antibodies used were raised against CD20, CD3, CD8, CD4 and granzyme B (Dako). EBV-encoded RNA (EBER) was probed on some specimen with the use of in situ hybridization technique. Slides were observed using a Leica DM LB microscope with ×20, ×40, and ×100 objectives and a 10× eyepiece. Aquisition of images was with IM50 software (Leica Microsystems). First line: CD8⁺ lymphocytic infiltrates in lobular (left) and portal (middle) area. Negative EBER staining (right). Second line: positive granzyme B staining in lobular and portal area (left and right panels, respectively). These infiltration could result of the trapping of the activated CD8⁺ T cells in liver during the immune response.¹⁰  (C) Immunoscope quantitative T-cell repertoire analysis. Most significant specific T-cell clonal expansion is shown. The x-axis indicates CDR3 length (in amino acid), and the y-axis displays the fluorescence intensity of the run-off products (in arbitrary units). Percentages indicate the frequency of occurrence for each Vβ family. (D) CD8⁺ maternal engrafted T cells express IFN-γ in response to EBV latent antigen LMP-2A antigen. Freshly isolated mononuclear cells of the patient and his mother were incubated without stimulation (NS) or in the presence of latent antigen LMP-2A, latent antigen EBNA-1, and lytic antigen BZLF-2, then stained for the expression of IFN-γ, CD3 and CD8. Numbers are the percentage of cells in the lymphoid gate expressing the indicated surface markers.