The kaolin agglutination test with three antigens used for detecting circulating antibodies against tuberculosis in humans, cattle and guinea-pigs

The kaolin agglutination test (KAT) has been applied to determine whether there is any difference in the results in various species (humans, cattle and guinea-pigs), and whether the antigens prepared from human and bovine types of Myco. tuberculosis, used separately or mixed together, could give similar information about the circulating antibodies against tuberculosis is various groups. The investigation revealed that more than 40% of tuberculous, patients were found to be serologically negative. On the other hand it was discovered that over 90% of healthy cows possessed a positive titre of KAT (1/8 and over) and more than 70% had a titre as high as 1/32 and over. None of the guinea-pigs infected with Myco. tuberculosis (human type) produced circulating antibodies against the infection organism, is spite of there being tuberculous lesions in the organs. From the above observations, it is suggested that humoral factors play different roles in protecting against tuberculosis in different species: low resistance to tuberculosis is associated with absence of humoral protection, and high resistance is associated with high levels of antiphosphatide antibodies and, possibly, some other humoral factors. The two antigens, from the human and bovine types, showed a good correlation in the results of KAT among individuals in both groups—human and bovine. The association between the KAT, immunity after BCG vaccination, tuberculin sensitivity and other factors are discussed and the results of the study are compared with those of other investigators. Le test d'agglutination au kaolin (KAT) a été utilisé afin de rechercher s'il existait une différence dans les résultats obtenus chez différentes espèces (homme, bétail et cobaye) et si les antigènes préparés à partir des types humain et bovine de Myco, tuberculosis, utilisés séparément ou en mélange, donnaient les mêmes informations sur les anticorps antituberculeux circulant dans les différents groupes. Cette étude a révélé que plus de 40% des malades tuberculeux sont sérologiquement négatifs. D'autre part, plus de 90% des vaches saines se sont révélées posséder un taux de KAT positif (1/8 et au delà) et plus de 70% atteignaient ou dépassaient le taux de 1/32. Aucun des cobayes infectés par Myco. tuberculosis (type humain) n'a produit d'anticorps circulants contre l'organisme infectant, bien que présentant des lésions tuberculeuses viscérales. Des observations précédentes on peut déduire que les facteurs humoraux jouent de