Relevance of lymphocyte proliferation to PHA in severe combined immunodeficiency (SCID) and T cell lymphopenia

Clin Immunol. 2024 Apr:261:109942. doi: 10.1016/j.clim.2024.109942. Epub 2024 Feb 15.

Abstract

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/μL, there was a higher proliferative response with the PHA flow assay compared to the 3H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID.

Keywords: Mitogen; PHA; PIDTC; SCID; Severe combined immunodeficiency; T-cell lymphopenia; T-cell proliferation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Proliferation
  • Humans
  • Infant, Newborn
  • Lymphopenia* / diagnosis
  • Neonatal Screening / methods
  • Severe Combined Immunodeficiency* / diagnosis
  • T-Lymphocytes