title: Inactivation of suppressor T cell activity by the nontoxic lipopolysaccharide of Rhodopseudomonas sphaeroides.
abstract: Antibody responses of mice immunized with type III pneumococcal polysaccharide were examined with and without treatment with nontoxic lipopolysaccharide from Rhodopseudomonas sphaeroides (Rs-LPS). The results obtained were similar to those described previously for mice treated with monophosphoryl lipid A (MPL) except that lower amounts of Rs-LPS were needed. Both were without effect when given at the time of immunization with type III pneumococcal polysaccharide but elicited significant enhancement when given 2 to 3 days later. Such enhancement was T cell dependent and not due to polyclonal activation of immunoglobulin M synthesis by B cells. Treatment with either Rs-LPS or MPL abolished the expression but not induction of low-dose paralysis, a form of immunological unresponsiveness known to be mediated by suppressor T cells (Ts). The in vitro treatment of cell suspensions containing Ts with extremely small amounts of Rs-LPS or MPI completely eliminated the capacity of such cells to transfer suppression to other mice. These findings indicate that the immunomodulatory effects of both MPL and Rs-LPS are mainly the result of eliminating the inhibitors effects of Ts; this permits the positive effects of amplifier T cells to be more fully expressed, thereby resulting in an increased antibody response. The significance of these and other findings to the use of Rs-LPS as a pharmacotherapeutic agent for gram-negative bacterial sepsis is discussed.
authors: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, Rockville, Maryland 20852.
authors: P J
authors: PJ
authors: Baker
authors: C E
authors: CE
authors: Taylor
authors: P W
authors: PW
authors: Stashak
authors: M B
authors: MB
authors: Fauntleroy
authors: K
authors: K
authors: Hasløv
authors: N
authors: N
authors: Qureshi
authors: K
authors: K
authors: Takayama
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D005260:Female; D007075:Immunoglobulin M / Q000276:immunology; D008050:Lipid A / Q000031:analogs & derivatives / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification / Q000494:pharmacology*; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007075:Immunoglobulin M; D008050:Lipid A; D011135:Polysaccharides, Bacterial; C026604:pneumococcal polysaccharide, type III; C048436:monophosphoryl lipid A