A quantitative assessment of primary and secondary immune responses in cattle using a B cell ELISPOT assay

Area of Science:

• Immunology
• Veterinary Medicine
• Cell Biology

Background:

• Understanding the dynamics of antigen-specific plasma cells and memory B cells is crucial for evaluating immune responses.
• The bovine model offers a valuable system for studying adaptive immunity relevant to both animal and human health.

Purpose of the Study:

• To develop and validate a method for detecting and quantifying antigen-specific plasma cells and memory B cells in bovine blood.
• To characterize the kinetics of these cell populations following ovalbumin immunization in calves.
• To correlate cell counts with antibody production and predict long-term immune memory.

Main Methods:

• Development of a novel assay for the detection and quantification of ovalbumin-specific plasma cells and memory B cells.
• Immunization of calves with ovalbumin to elicit primary and secondary immune responses.
• Monitoring of plasma cell and memory B cell populations in blood at various time points post-immunization.
• Measurement of anti-ovalbumin-specific antibody (Ab) titers.

Main Results:

• A distinct burst of ovalbumin-specific plasma cells was observed at days 6-7 during the primary response, followed by specific Ab production.
• Memory B cells increased gradually from day 15 during the primary response.
• A booster immunization induced a faster and stronger secondary response, with plasma cells peaking at days 3-4 and memory B cells at days 5-6.
• A strong correlation was found between IgG titers 5 months post-secondary immunization and peak plasma cell numbers after secondary immunization.

Conclusions:

• The developed method allows for effective detection and quantification of antigen-specific plasma and memory B cells in cattle.
• Plasma cell quantification in blood post-immunization can serve as a predictive marker for the magnitude and longevity of antibody responses.
• This approach has significant implications for vaccine efficacy assessment and immune monitoring in veterinary immunology.