Leukotrienes C4 and D4 sensitize human neutrophils for hyperreactivity to chemoattractants

To investigate the sensitizing effects of the cysteinyl leukotrienes (CysLTs) C(4) and D(4) on the proinflammatory responses of chemoattractant-activated human neutrophils in vitro.

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

Cells were exposed to LTC(4) and LTD(4) (50-300 nM) prior to activation with 1 microM of N-formyl-L-methionyl- L-leucyl-L-phenylalanine (fMLF).

A fura-2/AM-based spectrofluorimetric procedure, lucigenin-enhanced chemiluminescence (LECL), a colourimetric method and an ELISA procedure, were used to measure Ca(2+) mobilization, superoxide production, elastase and MMP-8 release respectively following activation of LTC(4)/ D(4)-primed neutrophils with fMLF. Superoxide generation was also measured in the presence and absence of the CysLT receptor 1 antagonist, montelukast (100 nM).

Exposure of neutrophils to either LTC(4) or LTD(4) alone had modest effects on Ca(2+) 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 LTC(4)or LTD(4) resulted in significant, augmentation of fMLF-activated elastase and MMP-8 release and superoxide generation, which was attenuated by montelukast.

These previously undocumented sensitizing interactions of LTs C(4) and D(4) 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.