IgG on human blood lymphocytes studied by immunofluorescence

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Surface immunoglobulins (sIg) are crucial B cell markers.
• Accurate quantification of sIg+ lymphocytes is essential for immunological studies.
• Non-specific IgG binding can lead to overestimation of sIg+ cells.

Purpose of the Study:

• To optimize immunofluorescence (IFL) methods for identifying surface immunoglobulins (sIg) on human lymphocytes.
• To investigate factors influencing the accurate detection of sIgG on B lymphocytes.
• To prevent overestimation of sIg+ B lymphocytes due to non-specific IgG absorption.

Main Methods:

• Immunofluorescence (IFL) staining of human blood lymphocytes.
• Use of conjugated F(ab'2) fragments of anti-Ig antibodies.
• Incubation and washing protocols at varying temperatures (37°C) and antibody types (F(ab'2) vs. undigested IgG).

Main Results:

• Approximately 20% of freshly isolated lymphocytes express sIgG.
• Incubation and washing at 37°C effectively removed Fc-receptor-bound polyclonal IgG.
• Using F(ab'2) fragments and 37°C washing prevented IgG absorption, yielding accurate sIg+ cell percentages.

Conclusions:

• Optimized IFL protocols using 37°C washing and F(ab'2) fragments are critical for accurate sIg+ B lymphocyte enumeration.
• These methods minimize non-specific IgG binding and absorption, preventing overestimation.
• The findings enhance the reliability of immunofluorescence assays in B cell research.