Correlation of Activated-Inflammatory T Cell Subtypes in Patients Tested for Lymphocyte Immunodeficiency

CD19negCD20dim T cells are mostly CD8+ and predominantly express memory markers. Based on the literature, they may be a subset of inflammatory T cells rather than a transient activated state. I postulated that CD19negCD20dim T cells would correlate with other signs of activated-inflammatory T cells. I examined blood from 100 consecutive patients referred for lymphocyte immune deficiency study, using the CD19negCD20dim expression on our B cell panel as a proxy for CD19negCD20dim T cells. I found a strong correlation between age and computed CD20dim T cells, which correlates with prior published findings. I separately analyzed 0–17-year-old children and 18–71-year-old adults. In both age groups, computed CD20dim T cells correlated well with age (Pearson p = 0.49 for pediatric, p = 0.45 for adult). Inspection of the data does not reveal any sharp inflection point in computed CD20dim T cells, and the percentage of computed CD20dim T cells did not differ by sex. When all subjects were examined, there was a weak positive correlation between computed CD20dim T cells and percentage of CD4+CD8+ “double-positive” (DP) T cells, percentage total T cells or CD8 T cells expressing HLA-DR, and an equally weak negative correlation with percentage TCRγδ T cells. However, none of the associations were statistically significant. Analyzing age groups separately, all correlations diminished in adults. However, in children, computed CD20dim T cells correlated well with T cell HLA-DR expression (Pearson p = 0.61) and with CD8 T cell HLA-DR expression (Pearson p = 0.52). I also compared the activated-inflammatory T cell markers with each other. Some weak correlations were noted (% DP T cells vs. % TCRγδ T cells in adults, p = -0.160; % HLA-DR vs. TCRγδ T cells in children, p = 0187), but none of the correlations was significant. The main conclusion is that computed CD20dim T cells correlated well with T cell HLA-DR expression and with CD8 T cell HLA-DR expression in children, but not in adults. Most markers of activated-inflammatory T cells did not correlate with each other and thus may represent distinct activation pathways.