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Delayed hypersensitivity testing as a clinical measure of cell-mediated immunity in the cat
C M Otto1, C A Brown, P A Lindl
1Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602.
Insights
The feline viral rhinotracheitis, calicivirus, and parvovirus (FVRCP) vaccine triggers a cell-mediated immune response in cats. An intradermal skin test effectively measures this feline immune function.
Area of Science:
- Veterinary Immunology
- Feline Infectious Diseases
Background:
- Assessing cell-mediated immunity in cats is crucial for understanding vaccine efficacy and disease progression.
- Modified-live vaccines like FVRCP are commonly used, but their immunologic impact requires detailed evaluation.
- The intradermal skin test is a potential tool for assessing feline immune responses.
Purpose of the Study:
- To investigate the cell-mediated immune response in normal cats following administration of a modified-live FVRCP vaccine.
- To determine the clinical utility of the intradermal skin test as a measure of feline immune response.
- To explore the correlation between vaccine-induced immune response and the presence of feline leukemia (FeLV) or feline immunodeficiency virus (FIV).
Main Methods:
- 34 normal adult cats received intradermal injections of the FVRCP vaccine or diluent on the dorsal pinna.
- Evaluated skin thickness, lymphocyte counts, and Concanavalin A mitogenesis indices in a subset of cats.
- Obtained skin biopsies for histological analysis and tested five cats with FeLV or FIV.
Main Results:
- The FVRCP vaccine induced a delayed hypersensitivity response in normal cats, with peak mononuclear infiltrate at 72 hours.
- Cats infected with FeLV or FIV exhibited a significantly diminished response to the intradermal skin test.
- Histological examination confirmed a mononuclear infiltrate characteristic of delayed hypersensitivity.
Conclusions:
- The intradermal skin test is a clinically useful method for evaluating immune function in cats.
- The FVRCP vaccine effectively elicits a cell-mediated immune response in healthy cats.
- The reduced skin test response in FeLV/FIV-positive cats suggests impaired immune function, potentially aiding in prognostic index development.
Abstract:
The purposes of this study were to examine the cell-mediated immune response of the normal cat to the modified live feline viral rhinitis, calicivirus, and parvovirus (FVRCP) vaccine (Felocell CVR, Norden, Lincoln, NE), and to evaluate the intradermal skin test as a clinical measure of the immune response of cats. Vaccine and diluent were injected intradermally on the dorsal pinna of 34 normal adult cats. Skin thickness measurements, lymphocyte counts, and Concanavalin A mitogenesis indices were evaluated in 18 of these cats. Skin biopsies were obtained in 16 cats. In normal cats, the FVRCP vaccine induced a delayed hypersensitivity response characterized by a mononuclear infiltrate most pronounced at 72 h. Five cats with either feline leukemia (FeLV) or feline immunodeficiency virus (FIV) were tested and had a significantly reduced response to the skin test. The skin test provides a clinically useful method of evaluating immune function in cats and may be useful in development of a prognostic index.
