Abstract:

Objective To investigate the effect of peripheral neutrophils on the positive degree of interferon-gamma release assay（IGRA）. Methods From October 2020 to March 2022，the whole blood of suspected tuberculosis patients were collected，according to ages they are classified into teenage（<40 years old），middle age（40-<60 years old） and elderly（≥60 years old） groups. Routine blood examination was performed. Peripheral blood mononuclear cells from tuberculosis patients were isolated for IGRA. The related data and determination results were collected. The results with spot number of test holes-blank control holes 11-14（close to cut-off value） were defined as weak positive，the results with more than 14 were defined as positive，and the results with less than 11 spots were defined as negative. The correlation between neutrophil count and positive degree of IGRA in patients of different ages and sex was analyzed. Two clinical cases were enrolled for verification. Results Among the 234 patients，neutrophil count in weakly positive group [（6.15±3.22）×10⁹/L] was higher than that in positive group [（5.05±2.66）×10⁹/L，P=0.030 2]. The neutrophil number in teenage weakly positive group [（7.54±4.46）×10⁹/L] was higher than that in positive group [（4.00±1.49）×10⁹/L，P=0.000 2]. The number of neutrophils in male patients with weakly positive group [（6.49±3.49）×10⁹/L] was higher than that in positive group [（5.28±2.54）×10⁹/L，P=0.040 8]. Clinical case verification results showed that patients with low neutrophil count were more likely to have positive IGRA results. Conclusions Neutrophil count affects the positive degree of IGRA，so the effect of neutrophils should be excluded in the auxiliary diagnosis of tuberculosis.

Key words: Neutrophil, Interferon-gamma release assay, Tuberculosis