IgA and IgA diphtheria antitoxin responses from human tonsil lymphocytes

Area of Science:

• Immunology
• Cell Biology

Background:

• Tonsils are key sites for immune responses to inhaled or ingested antigens.
• Understanding in vitro antibody production by human lymphocytes is crucial for vaccine development.

Purpose of the Study:

• To investigate the in vitro antibody production of human tonsil lymphocytes against diphtheria toxoid.
• To determine the factors influencing the in vitro antibody response, including prior immunization history.
• To characterize the immunoglobulin classes and polymeric forms of antibodies produced.

Main Methods:

• Human tonsil lymphocytes were stimulated with diphtheria toxoid in a Marbrook culture system.
• Antibody levels (IgG, IgA) in culture supernatants were quantified using radioimmunoassay with radiolabeled antigen.
• Immunoglobulin characterization involved immunodiffusion and sucrose density gradient ultracentrifugation.
• Neutralization assays were performed to confirm antitoxin activity.

Main Results:

• Significant IgG and IgA diphtheria antitoxin responses were observed in culture supernatants.
• Responding supernatants demonstrated toxin-neutralizing capacity.
• At least two diphtheria toxoid immunizations after six months of age were necessary to prime tonsils for an in vitro response.
• Approximately 40% of the produced IgA was polymeric (greater than 7S).
• Secretory piece was not detected on the produced IgA or specific IgA antitoxin.

Conclusions:

• Human tonsil lymphocytes can produce functional IgG and IgA diphtheria antitoxin in vitro.
• Prior immunization history significantly impacts the ability of tonsil lymphocytes to mount an in vitro antibody response.
• Human tonsil lymphocytes produce polymeric IgA in vitro, but it lacks secretory piece.