SALMONELLA-ENTERITIDIS IMMUNE LEUKOCYTE-STIMULATED SOLUBLE FACTORS - EFFECTS ON INCREASED RESISTANCE TO SALMONELLA ORGAN INVASION IN DAY-OLD LEGHORN CHICKS

Cytokines, derived from either concanavalin A-stimulated Salmonella en teritidis-immune chicken T lymphocytes [SE-immune Lymphocyte Stimulate d Soluble Factor (LSSF)] or lipopolysaccharide-stimulated SE-immune ch icken macrophages [SE-immune Macrophage Stimulated Soluble Factor (MSS F)], were evaluated for their ability to increase resistance to SE org an invasion in day-old Leghorn chicks. In Trial 1, day of hatch chicks were injected i.p. with either SE-immune LSSF or SE-nonimmune LSSF (c ontrol). In Trial 2, chicks were similarly injected with either SE-imm une MSSF, SE-nonimmune MSSF, or SE-immune LSSF (positive control). Thi rty minutes postinjection, all chicks were gavaged with an invasive do se of SE. Twenty-four hours later, livers and spleens from all chicks were cultured for SE. In Trial 1, SE-immune LSSF caused a rapid and ma rked protection (P < .01) against SE infection as determined by the nu mber of chicks that were culture positive regardless of challenge dose . In Trial 2, SE-immune MSSF was not associated with protection agains t SE organ infection. These experiments demonstrate that SE-immune LSS F, but not MSSF, are able to confer protection against SE organ invasi on in day-old Leghorn chicks. Thus, it appears that the stimulated imm une T cell, and not the macrophage, is responsible for producing the s oluble products that protected the chicks.