Objective: To investigate chemoattractant receptor homologous molecule expressed on Th2 cells (CRTh2)

cysteinyl leukotriene 1 receptor (CysLT1R) and histamine 1 receptor (H1R) expression and clinical significance in peripheral blood CD3+CD56+ natural killer T cells (NKT) of patients with bronchial asthma (BA). Methods: The peripheral blood of BA patients (BA group

n=40) and healthy control group (HC group

n=38) in The First Affiliated Hospital of Jinzhou Medical University from September 2020 to September 2021 were collected

and flow cytometry was used to detect the BA group and HC group expression of CRTh2

CysLT1R and H1R on CD3+CD56+ labeled NKT cells in peripheral blood. At the same time

its correlation with serum total immunoglobulin E (TIgE)

fractional exhaled nitric oxide (FeNO) and lung function forced expiratory volume in the first second/forced vital capacity% (FEV1/FVC%) were analyzed. Results: The percentage of NKT cells in the peripheral blood of the BA group[22.50 (15.78

29.20)] was lower than that in the HC group[27.90 (21.50

32.45)] (P=0.024). And in the further comparison

the percentage of CD3+ lymphocytes in the BA group[70.05 (63.20

78.45)] was lower than that in the HC group[73.70 (69.88

79.38)] (P=0.035). The percentage of CysLT1R in the BA group[0.08 (0.05

0.17)] was lower than that in the HC group[0.16 (0.10

0.34)] (P=0.004). The percentages of CRTH2 and H1R in the BA group[1.12 (0.53

1.88) ; 5.21 (1.41

10.10)] were not significantly different from those in the HC group[1.17 (0.60

4.25) ; 4.61 (1.42

8.53)] (P=0.234; P=0.697). Additionally

for the further comparison of the mean fluorescence intensity (MFI) of CRTh2 and H1R

BA group[925.52 (623.50

1 279.25)] CRTh2 MFI was lower than HC group[1 345.50 (891.00

1 977.75)] (P=0.002) ; there was no significant difference in H1R MFI between BA group[769 (657.50

975.00)] H1R MFI and HC group[835.00 (560.00

959.25)] (P=0.834). CD3+CD56+NKT cells had no significant correlation with serum TIgE and FeNO (r=-0.052; r=0.014)

but was positively correlated with the level of FEV1/FVC% (r=0.402

P=0.01). CRTH2 (r=0.166

r=-0.040)

CysLT1R (r=0.114

r=-0.150) and H1R (r=0.103

r=-0.096) had no significant correlation with TIgE and FeNO. Conclusion: CD3+CD56+NKT cells may play an important role in the pathogenesis of bronchial asthma

H1R may not be expressed on CD3+CD56+NKT cells

and the decreased expression of CRTh2 and CysLT1R on CD3+CD56+NKT cells in BA patients may provide a basis for accurate clinical diagnosis and treatment.