Specific serum agglutination of kaolin particles sensitized with tubercle phosphatide and its clinical evaluation as a serodiagnostic test for tuberculosis.

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There has already been evidence that three different kinds of antibodies completely distinct from each other (antipolysaccharide, antiprotein, and antiphosphatide) exist in tuberculous serum; and that, of the three antibodies, only the anti phosphatide as measured by the phosphatide hemagglutination test furnishes information about the activity or extent of tuberculous disease (1-3). In other studies a simple and reliable serologic test for measuring the anti phosphatide has been elaborated in this laboratory, using kaolin powder as the adsorbent agent (4, 5) and a special buffer solution made from tris (hydroxymethyl)aminomethane, maleic acid, and disodium ethylenediaminetetraacetate (referred to as TME buffer hereafter). It has also been found in this laboratory that the anti phosphatide is very susceptible to heating at 56°C. for 30 minutes, which is generally employed to inactivate serum. In fact, when test serum is heated for inactivation, the response of the antiphosphatide is depressed to almost less than one third as compared with unheated serum (6). This disadvantage is eliminated by replacing heat inactivation by chemical inactivation with disodium ethylenediaminetetraacetate (EDTA). In fact, this agent chelates Mg++ and Ca++ in test serum and thus indirectly inactivates the complement present without affecting the antiphosphatides. Thus, the phosphatide kaolin-agglutination test has been brought to its maximal sensitivity. Parallel to these observations, the phosphatide kaolin-agglutination test has been confirmed to be equivalent or rather superior to the phosphatide hemagglutination test, when EDTA is employed to inactivate serum. In the sequel, a