Technical Assistance

Abstract

In a series of earlier investigations by others (Rich and Lewis, 1932, Moen and Swift, 1936, Heilman, Feldman, and Mann, 1944 and preliminary reports from this laboratory (Favour, 1947, Favour, Fremont-Smith, and methods have been described for the study in vitro of tuberculin-type hypersensitivity. One feature of the tuberculin effect in vitro is the affinity of leucocytes from both tuberculin-negative as well as tuberculin-sensitive hosts for tuberculin . When white cells from non-tuberculous subjects are sensitized with tuberculin and exposed to a factor in the plasma from tuberculin-sensitive subjects, these cells undergo lysis (Miller, Favour, Wilson, and Umbarger, a, 1949). The lytic "plasma factor" is present in the euglobulin portion of blood, is heat labile (Miller, Favour, Wilson, and Umbarger, b, 1949), and requires complement for its specific effect (Miller, Vaughan, and Favour, 1949).In the present report experiments are described which indicate that "plasma factor" can be derived from the lymphocytes of the circulating blood of an appropriately sensitized host. Materials and MethodsSubjects.--Guinea pigs weighing 400 to 600 gin. were inoculated in the groins and pectoral regions with a total of 2.5 rag. of heat-killed tubercle bacilli (H37Rv) suspended in light mineral oil (Bayol F). The organisms were grown on the surface of a liquid medium described by Dubos and Middlebrook (Dubos and Middlebrook, 1947), the culture heated at 60°C. for 1 hour, and the bacteria lyophillzed following three washings and eentrifugations from distilled water. After 2 months the animals were reinjected with a similar quantity of heat-killed organisms. Individual guinea pigs showing palpable masses at the sites of inoculation and exhibiting intradermal induration of more than a centimeter in diameter 48 hours following the injection of 5 q, of PPD (Seibert and Glenn, 1941) were chosen for study. Normal uninoculated guinea pigs shown to be tuberculln-negative served as controls.