Detection of circulating immune complexes in the sera of dogs infected with Dirofilaria immitis, by Clq-binding enzyme-linked immunosorbent assay.

The presence of circulating immune complexes (CIC) in the sera of dogs infected with Dirofilaria immitis was detected by using a Clq-binding enzyme-linked immunosorbent assay. Specificity of this assay with different concentrations of heat-aggravated canine IgG (ACG) was observed, i.e., the ELISA readings, expressed as microgram equivalents ACG/ml, increased with increasing amounts of ACG. The intra-assay variability was below 10%. The CIC levels of infected and uninfected dogs were 177.0 +/- 104.7 micrograms/ml and 22.8 +/- 45.8 micrograms/ml (mean +/- SD), respectively. The highest level was observed in 12 dogs with amicrofilaraemic infection. Age distribution of CIC levels in the 23 infected dogs also showed a significant positive correlation. These findings suggested that the CIC are present in the sera of dogs with dirofilariasis and may relate to canine glomerulonephritis.