A screening for the occurrence of autoreactive antibodies in sera of pregnant and non-pregnant bitches.

Sera of healthy pregnant (group I, n = 11) and non-pregnant (group II, n = 11) bitches were screened for autoantibodies (AAb). In both groups, blood samples were drawn every fifth day between days 5 and 55 after mating. Serum was analysed via indirect immunofluorescence (IIF) with the Canine ANA HEp-2 Screening Kit. In all animals, anticytoplasmic AAb were detected. Utilizing primate-heart substrate slides AAb against contractile proteins of the cytoplasm could be observed. The predominating fluorescence pattern in pregnant animals resembled above all desmin, which was proven via Western blot. The sera were then pre-incubated with tropomyosin, actin, vimentin, vinculin and keratin solutions, and assessed on HEp-2 slides and on human and canine fibroblasts as well. The latter substrate was used to verify whether the detected Ab were in fact AAb. Utilizing tropomyosin, revealed elimination of the cytoplasmic fluorescences on all three substrates. It is therefore assumed, that in sera of healthy dogs, AAb against contractile structure proteins of the cytoplasm are present regularly. The majority of pregnant bitches presented with higher end-point titres (EPT), than to be found in non-pregnant dogs. AAb against desmin played the key role in those patterns. In addition, sera were screened for thyroid specific AAb, namely thyroglobulin, thyroid peroxidase (TPO), T3 and T4, and for AAb against insulin by ELISA or Western blot (TPO). Only in two of the pregnant bitches a weak positive reaction (1:100) for T3-AAb was detected.