Activated rat neutrophils. A sequential quantitative assay for aggregation and NBT reduction.

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Polymorphonuclear leukocytes (PMNs) play a crucial role in the innate immune system.
• Assessing PMN activation is vital for understanding immune responses and inflammatory conditions.
• Existing methods for PMN analysis can be time-consuming and require significant cell numbers.

Purpose of the Study:

• To develop a rapid, sensitive, and convenient assay for analyzing activated rat PMNs.
• To quantify PMN aggregation and nitroblue tetrazolium (NBT) reduction.
• To evaluate the effects of phorbol myristate acetate (PMA) and lipopolysaccharide (LPS) on rat PMNs.

Main Methods:

• Utilized an ELISA scanner to quantify optical densities of cell cultures in microtiter plates.
• Measured PMN aggregation and NBT reduction in response to various stimuli, including PMA, LPS, and lymphokine-containing rat serum.
• Employed blocking studies with 2-deoxyglucose, iodoacetamide, and polymyxin B to validate the assays.

Main Results:

• The assay detected PMN aggregation induced by as little as 0.005 µg/ml PMA or 0.01 µg/ml LPS.
• NBT reduction was induced by 0.01 µg/ml PMA.
• Rat PMNs showed lower sensitivity to LPS and slower NBT reduction compared to human PMNs.

Conclusions:

• The developed method is rapid, sensitive, and convenient for analyzing rat PMN activation.
• The assay allows for simultaneous or sequential measurement of PMN aggregation and NBT reduction.
• This technology is attractive for studying immune cell responses due to its speed, low cell requirement, and simplicity.