Detection of Toxoplasma gondii-specific IgA in the aqueous humor of cats
Lappin, M.R.; Burney, D.P.; Hill, S.A.; Chavkin, M.J.
American Journal of Veterinary Research 56(6): 774-778
1995
ISSN/ISBN: 0002-9645 PMID: 7653887 Document Number: 446215
Toxoplasma gondii-specific IgA, IgM, and IgG were measured by ELISA in the serum and aqueous humor of 29 client-owned cats with endogenous uveitis and 7 specific-pathogen-free cats tested sequentially for 20 weeks after inoculation with T. gondii. Local antibody production in aqueous humor was estimated by multiplying the aqueous humor-to-serum T. gondii-specific antibody ratio by the serum-to-aqueous humor total IgG (C value) or calicivirus-specific IgG (CTC value) ratio. Evidence for local production of antibody in aqueous humor was defined as C value greater than 8 or C-TC value greater than 1. Toxoplasma gondii-specific IgM C-TC values, IgG C-TC values, or IgA C-TC values greater than 1 were detected in the aqueous humor of 18 of 29 (62.1%) client-owned cats with endogenous uveitis; 2 cats had IgA C-TC values greater than 1 without detectable IgM or IgG in aqueous humor. Toxoplasma gondii-specific IgM was not detected in the aqueous humor of experimentally inoculated cats before or after inoculation. Immunoglobulin G C values greater than 8 were detected in all 7 experimentally inoculated cats and ranged from 10.4 to 145.5. Immunoglobulin G C values greater than 8 were first detected 4 to 8 weeks after T. gondii inoculation and were undetectable by week 16 after inoculation. Immunoglobulin A C values greater than 8 were detected in 4 of 7 cats and ranged from 12.7 to 264.3. Immunoglobulin A C values greater than 8 were first detected 4 to 8 weeks after inoculation, and were detected in 2 cats during week 20 after inoculation. It was concluded that some cats infected with T. gondii develop detectable concentrations of T. gondii-specific IgA in aqueous humor.