Circulating immune-complexes and analysis of renal immune deposits in Feline Immunodeficiency Virus-infected Cats

Total immunoglobulin content and concentration of immune complexes (IC) were determined in the sera of 51 cats infected with feline immunodeficiency virus (FIV) and of 40 controls. IgG and IgM were quantified by radial immunodiffusion and circulating IC (CIC) by the CIC-conglutinin assay. IgG fractions were obtained by acid elution from kidney tissues of 15 FIV-infected and five negative control cats to investigate the possible role of IC in the genesis of renal damage observed in infected animals. Mean concentrations of IgG and circulating IC were higher in FIV-infected cats than in controls (29.6+/-6.7 versus 23.0+/-1.9 mg/dl (mean+/-s.d.) P<0.001; and 66.5+/-17.0 versus 27.4+/-19.9% I, P<0.001, respectively), while IgM levels were only slightly increased (0.9+/-0.05 vep sus 0.87+/-0.04 mg/dl, P