Clinical Value of Proliferated T Lymphocytes With Aberrant Immunophenotypes in Childhood HLH

Goal of this study was to investigate distribution of 3 aberrant immunophenotypes of T cells in childhood Hemophagocytic lymphohistiocytosis (HLH), and to find their relations with treatment responses and long-time outcomes.

Aberrant T cell immunophenotypes presented by patients with HLH at diagnosis during Jan 2018 to Oct 2021 were collected. Distributions of these immunophenotypes among different HLH groups and their relations with first-line therapy responses or lone-time outcomes of patients were studied.

T cell populations with aberrant immunophenotypes were found in 40 patients out of 189 (21.2%). Aberrant immunophenotypic patterns were divided into 3 categories: CD38 + HLA-DR + (N=11, 27.5%), clonal expression of TCRVb (N=17, 42.5%), or down regulation of surface CD5 (N=28, 70.0%). Statistical results showed that T cells from patients with EBV-HLH were prone to present 1 or more of these 3 aberrant immunophenotypes ( P <0.001), and that most cases (4/6) with CD4 + T cells with aberrant immunophenotypes were in CAEBV-HLH group. Although plasma levels of IFN-γ were higher in patients with these immunophenotypes ( P =0.01), no significant relation was found between these aberrant T cell immunophenotypes and treatment response or long-time outcome. Besides, no hematologic malignancies developed in patients with aberrant T cell immunophenotypes throughout follow up.

Patients with HLH frequently show aberrant immunophenotypes of T cells. In most cases, this immunophenotypic patterns have connection to severity, but not outcome of the disease.