Background/Purpose: We have previously reported that CD38 gene expression in the peripheral blood T cell from patients with SLE is increased. CD8⁺CD38⁺ T cells have impaired cytotoxicity leading to increased risk of infections. The purpose of the current study was to further investigate whether the expansion of CD8⁺CD38⁺ T cells in patients with SLE predicts increased load of infectious episodes.

Methods: CD38 surface expression was measured by flow cytometry in fresh T cells from patients with SLE (n=43) over a period of time ranging from 6 to 24 months. The expression of CD38 on the surface of T cells was estimated my flow cytometry. Clinical parameters (SLEDAI, flare rate and medications) as well as rate and type of infections were recorded from patients with SLE for further analysis.

Results: CD38 surface expression was higher in CD8+ T cells from patients with SLE (30%±3, n=37) compared to normal controls (18.7% 1, n=18, p< 0.001). Within group of patients with SLE we identified two groups of patients: those with high ( > 28.9%; mean +2 standard deviations of normal values) and those with low (< 28.9%) expression levels of CD38. We followed these patients longitudinally and recorded number of infections over the study period. 43 subjects were found to had two or more visits. Interestingly, 23 out of the 30 SLE patients with lower percentage of CD8+CD38+ T cells did not report any infections at the initial visit compared with 4 out of the 14 SLE with higher CD8+CD38+ percentages who reported at least one infectious episode (p< 0.01 using Chi-squared test). Even more, patients with SLE who had a higher percentage of CD8+CD38+ T cells (n=32) at their initial visit were more prone to developing subsequent infections (1.1 infections/year) compared to those with low percentage of CD8+CD38+ cells (n=14, 0.7 infection/year, p=0.05). Early analyses did not reveal an association with disease activity and treatment.

Conclusion: Our data indicate that increased percentage of CD8⁺CD38⁺ T cells in the peripheral blood of patients with SLE predicts increased numbers of infections. Identification of this subset of patients should alert care-takers to expect, identify and treat promptly in order to limit morbidity and mortality.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/high-expression-of-cd38-on-cd8-t-cells-predicts-increased-burden-of-infections-in-patients-with-sle/