The Production of Antibodies in Rabbits by a Simplified Intratracheal Method

The method described of producing antibodies by the administration of antigens through the larynx is simple. The results obtained, however, conform closely to those obtained through intraperitoneal injection. The procedure is relatively a safe one and may well be employed in experimental inoculations. The advantages of rapidity and painlessness are obvious. In addition, gross injury has not been observed. Injections may be repeated at frequent intervals without danger to the life of the animal. The tube illustrated in Text-fig. 1 extends a little over 1 cm. into the trachea. The tube designed for the guinea pig reaches 2 or 3 mm. below the glottis. While the doses indicated in the protocols are small, 7 to 10 cc. of liquid have been given to rabbits by means of the tube without ill effects. It has been shown by the injection of India ink that the material is well distributed throughout the lungs in both the rabbit and guinea pig. Under certain conditions it may be advisable to inject more deeply into the trachea, especially in the rabbit. The tube illustrated in Text-fig. 1 is not adaptable for this purpose. A cannula of larger diameter has proved of distinct advantage as a shield for introducing flexible catheters well down the trachea. A cannula 9 cm. long and 4 mm. in diameter when bent at an angle of 45 degrees may be passed through the larynx of a rabbit without difficulty. A No. 8 (French) woven or No. 10 soft rubber catheter may be inserted into the cannula beyond the bend before the tube is passed through the glottis. After the tube has entered the glottis the catheter then may be introduced as deeply as desired into the teachea. The metal cannula enables the operator to "feel" the glottis. From the experiments one seems justified in concluding that the results obtained by administering antigens by way of the trachea are about the same as those obtained by the intraperitoneal route. With the tubes described injury has been largely eliminated. The procedure is relatively a safe one.