A cytofluorometric method to quantify membrane antigens on individual alveolar macrophages

Area of Science:

• Immunology
• Cell Biology
• Respiratory Medicine

Background:

• Alveolar macrophages (AM) play a crucial role in lung immunity.
• Assaying membrane-bound antigens on AM is vital for understanding lung diseases.
• Existing methods face challenges with AM autofluorescence.

Purpose of the Study:

• To develop and validate a reliable immunofluorescence method for quantifying membrane-bound antigens on individual AM.
• To address and correct for autofluorescence in AM, particularly from smokers.

Main Methods:

• Bronchoalveolar lavage (BAL) was used to collect alveolar macrophages.
• Direct immunofluorescence labeling with FITC-conjugated anti-HLA-DR antibodies.
• Computer-assisted cytophotometry for fluorescence quantification.
• A dual-wavelength approach to differentiate specific and non-specific fluorescence.

Main Results:

• The described method accurately quantifies specific fluorescence from membrane-bound antigens on AM.
• Autofluorescence in AM, especially from smokers, was identified as a significant interference.
• A novel correction strategy involving measurements at different wavelengths was successfully implemented.
• The method demonstrated specificity and reproducibility, confirming its reliability.

Conclusions:

• This immunofluorescence assay provides a reliable tool for studying AM surface antigens.
• The method effectively overcomes the challenge of AM autofluorescence.
• It is applicable to AM obtained from various sources, including cigarette smokers.
• This technique enhances the study of macrophage function in respiratory health and disease.