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A sequential study of the bovine tuberculin reaction
M L Doherty1, H F Bassett, P J Quinn
1Faculty of Veterinary Medicine, University College Dublin, Ballsbridge, Ireland.
Immunology
|January 1, 1996
Summary
The tuberculin reaction in cattle involves distinct early and late phases of immune cell infiltration and inflammation following purified protein derivative (PPD) injection. These changes are similar in experimentally sensitized and naturally infected animals.
Area of Science:
- Veterinary Pathology
- Immunology
- Bovine Medicine
Background:
- The tuberculin skin test is crucial for diagnosing bovine tuberculosis (TB).
- Understanding the cellular and molecular dynamics of the tuberculin reaction is vital for accurate TB diagnosis in cattle.
Purpose of the Study:
- To investigate the sequential histopathological and immunocytochemical changes during the tuberculin reaction in cattle.
- To compare these changes in cattle experimentally sensitized to Mycobacterium bovis and naturally infected with M. bovis.
Main Methods:
- Experimental sensitization and natural infection models with Mycobacterium bovis in cattle.
- Intradermal injection of purified protein derivative (PPD).
- Histopathological and immunocytochemical analysis at various time points (6 hr to 72 hr post-injection).
Main Results:
- Two distinct phases of reaction were observed, similar in both experimental and naturally infected cattle.
- Early phase (6-24 hr): perivascular aggregation of gamma delta T cells, neutrophils, and leucocytoclastic vasculitis.
- Late phase (24-72 hr): increased infiltration of CD4+ T cells, CD8+ T cells, macrophages, and elevated IL-2 receptor expression, with macrophages being predominant.
Conclusions:
- The tuberculin reaction in cattle progresses through distinct temporal phases involving specific immune cell populations.
- The observed inflammatory response, characterized by edema and fibrin deposition, contributes to skin thickening.
- Findings support the utility of the tuberculin skin test in diagnosing bovine tuberculosis by revealing characteristic cellular changes.