Leukotrienes C₄ and D₄ sensitize human neutrophils for hyperreactivity to chemoattractants

Abstract.

Objective and design:

To investigate the sensitizing effects of the cysteinyl leukotrienes (CysLTs) C₄ and D₄ on the proinflammatory responses of chemoattractant-activated human neutrophils in vitro.

Materials:

Neutrophils were isolated from venous blood taken from healthy, adult, human volunteers.

Treatment:

Cells were exposed to LTC₄ and LTD₄ (50–300 nM) prior to activation with 1 μM of N-formyl-L-methionyl- L-leucyl-L-phenylalanine (fMLF).

Methods:

A fura-2/AM-based spectrofluorimetric procedure, lucigenin-enhanced chemiluminescence (LECL), a colourimetric method and an ELISA procedure, were used to measure Ca²⁺ mobilization, superoxide production, elastase and MMP-8 release respectively following activation of LTC₄/ D₄-primed neutrophils with fMLF. Superoxide generation was also measured in the presence and absence of the CysLT receptor 1 antagonist, montelukast (100 nM).

Results:

Exposure of neutrophils to either LTC₄ or LTD₄ alone had modest effects on Ca₂₊ mobilization, while superoxide generation and elastase release were unaffected. However, relative to the responses of neutrophils activated with fMLF in the absence of the CysLTs, pre-treatment of the cells with either LTC₄or LTD₄ resulted in significant, augmentation of fMLF-activated elastase and MMP-8 release and superoxide generation, which was attenuated by montelukast.

Conclusion

These previously undocumented sensitizing interactions of LTs C₄ and D₄ with neutrophils may contribute to the activation of these cells in acute and chronic inflammation of both atopic and non-atopic aetiology, while identifying a role for montelukast in regulating neutrophil reactivity.