STUDIES ON THE ISOLATION AND CHARACTERIZATION OF A REAGINIC ANTIBODY IN A CAT

A reaginic antibody has been demonstrated, by passive cutaneous anaphy laxis (PCA), in the serum of a cat infected with the microfilariae of Brugia pahangi. Recipient cats and pigs were challenged with an extrac t of Ascaris suum after either a four-hour or a 72-hour period of sens itisation. When the serum was heat treated at 56 degrees C it lost its PCA activity. Gel filtration of the serum revealed a pattern of posit ive PCA fractions similar to that observed in other species. Attempts to purify the PCA-positive material by Superose gel filtration and ion exchange chromatography by fast protein liquid chromatography (FPLC) were unsuccessful. Affinity chromatography of PCA-positive material by FPLC on protein A demonstrated two bound peaks, the second of which w as PCA-positive and eluted as a single peak by ion exchange chromatogr aphy. The PCA-positive material from gel filtration did not bind to pr otein G. The protein A, PCA-positive peak provides a partially purifie d reaginic antibody for further study.