Pertussis toxin inhibits chemotactic factor-induced phospholipase C stimulation and lysosomal enzyme secretion in...

Area of Science:

• Cellular and Molecular Immunology
• Biochemistry

Background:

• Neutrophils play a crucial role in the immune response.
• Chemoattractants like fMet-Leu-Phe and leukotriene B4 activate neutrophil signaling pathways.
• Pertussis toxin is known to affect G protein-coupled receptors.

Purpose of the Study:

• To investigate the role of pertussis toxin in neutrophil signaling.
• To explore the involvement of guanine nucleotide-binding proteins in fMet-Leu-Phe and leukotriene B4 responses.

Main Methods:

• Measurement of [32P]polyphosphoinositide breakdown in rabbit neutrophils.
• Assay of lysosomal enzyme secretion.
• Quantification of [3H]inositol trisphosphate accumulation.
• Treatment with pertussis toxin to assess its inhibitory effects.

Main Results:

• Pertussis toxin suppressed fMet-Leu-Phe-induced [32P]polyphosphoinositide breakdown and lysosomal enzyme secretion.
• The toxin also inhibited fMet-Leu-Phe- or leukotriene B4-evoked [3H]inositol trisphosphate accumulation.
• Pertussis toxin specifically inactivates the guanine nucleotide-binding protein (Ni).

Conclusions:

• Guanine nucleotide-binding proteins (Ni) are implicated in mediating the effects of calcium-mobilizing receptors in rabbit neutrophils.
• These proteins likely couple calcium-mobilizing receptors to phospholipase C-mediated reactions.
• The findings highlight the role of G proteins in neutrophil activation pathways.