We present the results of a multicenter clinical trial using Epstein-Barr virus (EBV)–specific cytotoxic T lymphocytes (CTLs) generated from EBV-seropositive blood donors to treat patients with EBV-positive posttransplantation lymphoproliferative disease (PTLD) on the basis of the best HLA match and specific in vitro cytotoxicity. Thirty-three PTLD patients who had failed on conventional therapy were enrolled. No adverse effects of CTL infusions were observed and the response rate (complete or partial) in 33 patients was 64% at 5 weeks and 52% at 6 months. Fourteen patients achieved a complete remission, 3 showed a partial response, and 16 had no response at 6 months (5 died before completing treatment). At 5 weeks, there was a significant trend toward better responses with higher numbers of CD4⁺ cells in infused CTL lines (P = .001) that were maintained at 6 months (P = .001). Patients receiving CTLs with closer HLA matching responded better at 6 months (P = .048). Female patients responded better than male patients, but the differences were not statistically significant. Our results show that allogeneic CTLs are a safe and rapid therapy for PTLD, bypassing the need to grow CTLs for individual patients. The response rate in this poor prognosis patient group is encouraging.

Key Points: DLBCL can be detected in the blood by immunoglobulin high-throughput sequencing (Ig-HTS) with high specificity. Although DLBCL can be detected in leukocytes or plasma by Ig-HTS, plasma has greater sensitivity and more accurately reflects disease.

Key Points: Expansion of PD-1+ CD3−CD56hiCD16-ve NK cells and PD-L1+ monocytes/macrophages is more prominent in cHL than DLBCL. PD-1 blockade reverses the immune evasion mediated by the interaction of PD-1+ NK cells and PD-L1+ monocytes/macrophages.

In Hodgkin lymphoma (HL), the malignant Hodgkin Reed-Sternberg (HRS) cells constitute only 0.5% of 10% of the diseased tissue. The surrounding cellular infiltrate is enriched with T cells that are hypothesized to modulate antitumor immunity. We show that a marker of regulatory T cells, LAG-3, is strongly expressed on infiltrating lymphocytes present in proximity to HRS cells. Circulating regulatory T cells (CD4⁺ CD25^hi CD45 RO^hi, CD4⁺ CTLA4^hi, and CD4⁺ LAG-3^hi) were elevated in HL patients with active disease when compared with remission. Longitudinal profiling of EBV-specific CD8⁺ T-cell responses in 94 HL patients revealed a selective loss of interferon-γ expression by CD8⁺ T cells specific for latent membrane proteins 1 and 2 (LMP1/2), irrespective of EBV tissue status. Intratumoral LAG-3 expression was associated with EBV tissue positivity, whereas FOXP3 was linked with neither LAG-3 nor EBV tissue status. The level of LAG-3 and FOXP3 expression on the tumor-infiltrating lymphocytes was coincident with impairment of LMP1/2-specific T-cell function. In vitro pre-exposure of peripheral blood mononuclear cells to HRS cell line supernatant significantly increased the expansion of regulatory T cells and suppressed LMP-specific T-cell responses. Deletion of CD4⁺ LAG-3⁺ T cells enhanced LMP-specific reactivity. These findings indicate a pivotal role for regulatory T cells and LAG-3 in the suppression of EBV-specific cell-mediated immunity in HL.

Human CMV (HCMV) infection provides an informative model of how long term human CD8+ T cell memory is maintained in the presence of Ag. To clarify the phenotypic identity of Ag-experienced human CD8+ T cells in vivo, we determined the expression of costimulation and chemokine receptors on Ag-specific CD8+ T cells by quantifying individual virus-specific clones in different cell populations using TCR clonotypic probing. In healthy HCMV carriers, expanded CD8+ clones specific for either HCMV tegument protein pp65 or immediate-early protein IE72 are found in both CD45ROhigh cells and the subpopulation of CD45RAhigh cells that lack the costimulatory molecule CD28. In contrast to previous suggested models of CD8+ T cell memory, we found that in healthy virus carriers highly purified CD28−CD45RAhighCCR7− cells are not terminally differentiated, because following stimulation in vitro with specific HCMV peptide these cells underwent sustained clonal proliferation, up-regulated CD45RO and CCR5, and showed strong peptide-specific cytotoxic activity. In an individual with acute primary HCMV infection, HCMV pp65-specific CD8+ T cells are predominantly CD28−CD45ROhighCCR7−. During convalescence, an increasing proportion of pp65-specific CD8+ T cells were CD28−CD45RAhighCCR7−. We conclude that naive human CD8+ T cells are CD28+CD45RAhigh, express CCR7 but not CCR6, and are predominantly CD27+ and L-selectin CD62 ligand-positive. The phenotype CD27+CD45RAhigh should not be used to identify naive human CD8+ T cells, because CD27+CD45RAhigh cells also contain a significant subpopulation of CD28−CD27+ Ag-experienced expanded clones. Thus CD8+ T cell memory to HCMV is maintained by cells of expanded HCMV-specific clones that show heterogeneity of activation state and costimulation molecular expression within both CD45ROhigh and CD28−CD45RAhigh T cell pools.