[Alpha 1-antitrypsin/lymphocyte interactions: cytofluorometry study].

Area of Science:

• Immunology
• Biochemistry

Context:

• Previous studies indicated alpha 1-antitrypsin (alpha 1AT) inhibits immune responses.
• Radiolabeling studies showed alpha 1AT binding to lymphocytes and inhibiting surface proteolytic activity.
• Limitations of radiolabeling included inability to assess alpha 1AT distribution or presence on untreated cells.

Purpose:

• To investigate the presence and distribution of alpha 1AT on untreated human lymphocytes.
• To determine if additional alpha 1AT binds to lymphocytes and assess the specificity of this interaction.
• To explore methods for displacing bound alpha 1AT from lymphocyte surfaces.

Summary:

• Indirect fluorescence and flow cytometry revealed alpha 1AT on a variable percentage of untreated peripheral blood and tonsillar lymphocytes.
• Incubation with exogenous alpha 1AT increased the percentage of fluorescent lymphocytes, indicating binding.
• Binding was specific and could be inhibited by tosyl-L-phenylalanine-chloromethyl-ketone (TPCK); TPCK and EDTA displaced pre-bound alpha 1AT.

Impact:

• Demonstrates the presence of endogenous alpha 1AT on lymphocytes, suggesting a role in immune cell function.
• Provides a non-radiolabeling method to study alpha 1AT-lymphocyte interactions.
• Identifies specific inhibitors and conditions for modulating alpha 1AT binding to lymphocytes, relevant for immunomodulatory therapies.