Peripheral T-cell lymphoma with a regulatory T-cell phenotype: report of a nodal and an extranodal case from Peru

CD3+CD4-CD8- (Double-Negative) T Cells in Inflammation, Immune Disorders and Cancer

The crucial role of CD4⁺ and CD8⁺ T cells in shaping and controlling immune responses during immune disease and cancer development has been well established and used to achieve marked clinical benefits. CD3⁺CD4^-CD8^- double-negative (DN) T cells, although constituting a rare subset of peripheral T cells, are gaining interest for their roles in inflammation, immune disease and cancer. Herein, we comprehensively review the origin, distribution and functions of this unique T cell subgroup. First, we focused on characterizing multifunctional DN T cells in various immune responses. DN regulatory T cells have the capacity to prevent graft-versus-host disease and have therapeutic value for autoimmune disease. T helper-like DN T cells protect against or promote inflammation and virus infection depending on the specific settings and promote certain autoimmune disease. Notably, we clarified the role of DN tumor-infiltrating lymphocytes and outlined the potential for malignant proliferation of DN T cells. Finally, we reviewed the recent advances in the applications of DN T cell-based therapy for cancer. In conclusion, a better understanding of the heterogeneity and functions of DN T cells may help to develop DN T cells as a potential therapeutic tool for inflammation, immune disorders and cancer.

FOXP3-positive T-cell lymphomas in non-HTLV1 carriers include ALK-negative anaplastic large cell lymphoma: expanding the spectrum of T-cell lymphomas with regulatory phenotype

Forkhead box P3 (FOXP3) is a specific marker for regulatory T-cells (Tregs). We report 6 cases of T-cell lymphomas with Treg phenotype based on diffuse positivity for FOXP3 in tumor cells. The patients showed a median age of 56 years with a male predominance. Sites of disease included lymph nodes (4), skin (2), subcutaneous tissue (1) and bone marrow (1). All cases showed monomorphic large cells, some with Hodgkin-like or anaplastic cells. All cases expressed pan T-cell markers and lacked cytotoxic markers; one case showed diffuse PD1 staining. Only one case harbored human T-lymphotrophic virus (HTLV)-1 DNA within tumor cells and was classified as adult T-cell leukemia/lymphoma (ATLL). Among 5 HTLV1-negative cases, 3 were classified as peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) and 2 fulfilled criteria for ALK-negative anaplastic large cell lymphoma (ALCL) with diffuse and strong CD30 positivity. We concluded that Treg phenotype may be rarely seen in HTLV1-negative cases, such as PTCL, NOS and ALK-negative ALCL. Our findings expand the spectrum of T-cell lymphomas with regulatory phenotype and suggest that consideration should be given to HTLV1 DNA testing in the appropriate clinical setting to rule out ATLL.

FoxP3-positive T cell lymphoma arising in non-HTLV1 carrier: clinicopathological analysis of 11 cases of PTCL-NOS and 2 cases of mycosis fungoides

AIMS

Forkhead box protein 3-positive (FoxP3(+) ) T cell lymphoma, in the absence of human T cell lymphotrophic virus type 1 (HTLV-1) infection, is rare and its clinicopathological characteristics still remain unclear. The aim of this study was to elucidate its characteristics.

METHODS AND RESULTS

We describe here 11 cases of peripheral T cell lymphoma not otherwise specified (PTCL-NOS) and two cases of mycosis fingoides (MF) which were positive for FoxP3. The median age of the 11 PTCL-NOS cases was 65 years (range: 48-80 years), and all the patients were male. Eight patients (80%) showed stages III/IV disease, and six (60%) were categorized as high-intermediate/high-risk groups according to the International Prognostic Index. Two cases of MF were 57- and 59-year-old males. Both cases were categorized as stage IA, according to International Society for Cutaneous Lymphomas/European Organization of Research and Treatment of Cancer (ISCL/EORTC) classification. Immunohistochemically, all the cases were negative for cytotoxic molecule marker, and nine (75%) were αβ T cell type. Scattered Epstein-Barr virus (EBV)-infected cells were detected in four cases of PTCL-NOS, implying the reactivation of EBV caused by the immunodeficient status of the patients.

CONCLUSIONS

FoxP3(+) PTCL-NOS constitute a minor phenotypical subtype with poor prognosis and EBV reactivation in some. Conversely, two cases of MF showed an indolent clinical course which was different from previously reported cutaneous T cell lymphoma (CTCL) cases.

The four types of Tregs in malignant lymphomas

Regulatory T cells (Tregs) are a specialized subpopulation of CD4⁺ T cells, which act to suppress the activation of other immune cells. Tregs represent important modulators for the interaction between lymphomas and host microenvironment. Lymphomas are a group of serious and frequently fatal malignant diseases of lymphocytes. Recent studies revealed that some lymphoma T cells might adopt a Treg profile. Assessment of Treg phenotypes and genotypes in patients may offer prediction of outcome in many types of lymphomas including diffuse large B-cell lymphoma, follicular lymphoma, cutaneous T cell lymphoma, and Hodgkin's lymphoma. Based on characterized roles of Tregs in lymphomas, we can categorize the various roles into four groups: (a) suppressor Tregs; (b) malignant Tregs; (c) direct tumor-killing Tregs; and (d) incompetent Tregs. The classification into four groups is significant in predicting prognosis and designing Tregs-based immunotherapies for treating lymphomas. In patients with lymphomas where Tregs serve either as suppressor Tregs or malignant Tregs, anti-tumor cytotoxicity is suppressed thus decreased numbers of Tregs are associated with a good prognosis. In contrast, in patients with lymphomas where Tregs serve as tumor-killing Tregs and incompetent Tregs, anti-tumor cytotoxicity is enhanced or anti-autoimmune Tregs activities are weakened thus increased numbers of Tregs are associated with a good prognosis and reduced numbers of Tregs are associated with a poor prognosis. However, the mechanisms underlying the various roles of Tregs in patients with lymphomas remain unknown. Therefore, further research is needed in this regard as well as the utility of Tregs as prognostic factors and therapy strategies in different lymphomas.