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STIMULATORY PROPERTIES OF LEGIONELLA PNEUMOPHILA DERIVED LIPOPOLYSACCHARIDE IN VIVO AND IN VITRO, Catherine Newton, Raymond Widen, Thomas Klein and Herman Friedman, University of South Florida College of Medicine, Tampa, FL (U.S.A.)

It is widely accepted that most, if not all bacterial endotoxins are strong adjuvants and markedly stimulate the immune response system of man and experimental animals, both in vivo and in vitro. Legionella pneumophila, the newly described etiologic agent of legion- ellosis, is an ubiquitous Gram negative organism and as potent as myeobaeteria in poten- tiating antibody responses to weakly immunogenic antigens. The lipopolysaccharide (LPS)- rich antigens of this organism are distinct from those derived from other Gram negative organisms and have unique physicochemical properties. Intact legionellae, as well as cell free sonicates or purified LPS containing cell wall preparations, are adjuvantic for mice or guinea pigs. The immune response to antigens such as sheep RBCs is markedly potentiated in animals given Legionella LPS. Legionella endotoxin is also a strong mito- gen for normal mouse spleen cells and induced heightened blastogenic response of spleen cells from guinea pigs and mice which had been either immunized or sensitized to the in- tact bacteria. Legionelia antigens and LPS stimulate cytokine formation in mouse spleno- cyte culture in vitro. Interleukin 1 and interferons are induced by Legionella LPS when added to normal spleen cell cultures. IL-2 developed in spleen cell cultures from immune or sensitized animals. Thus it is apparent that legionella LPS, although biochemically distinct from LPS from other enterobactericeae, is not only a potent adjuvant but also a potent stimulator of cytokine formation in vitro.

GLUCANS AS IMMUNOMODIFIERS I

A COMPARATIVE EVALUATION OF PARTICULATE AND SOLUBLE GLUCAN IN AN ENDOTOXIN MOOEt G .J . Bowers, M . L . Patchen, T . J . MacVitt ie, R. Nelson, and M.P . Fink The Armed Forces Radiobiology Research Inst i tute , Bethesda , MD, USA P a r t i c u l a t e glucan (P) but not soluble glucan (F) sensitizes rats to endotoxins (LPS) . This phenomenon is bel ieved to be mediated by the ret iculoendothel ial system (RES) . The ef fect o f glucan--P and -F on the RES as well as the response of glucan treated rats to n o n l e t h a l doses o f LPS w e r e i n v e s t i g a t e d . Rats w e r e i n j e c t e d f o r . 5 days w i t h 3 mg g lucan -P • -F o r saline. Three days later rats were e i ther (1} injected with colloidal c a r b o n fo r clearance studies, (2) sacrif iced for organ histology and baseline blood work , o r (3 ) c h a l l e n g e d w i t h a non le tha l dose of e n d o t o x i n . G r o u p 3 r a t s w e r e f u r t h e r s u b d i v i d e d in to g roups fo r 30-day s u r v i v a l s tud ies and for sacrif ice at 30 rains or 4 hrs to obtain serum s~amples fo r g lucose th romboxane A_ and p r o s t a c y c l i n . Glucan-P induced • z hepa tosp lenomega ly and g ranu lomatous changes w i t h i n the l iver and spleen. The carbon c learance halft ime was markedly decreased in these animals. Following LPS, there were s i g n i f i c a n t increases in both serum pros tano ids in g lucan-P animals as well as alterations in serum glucose levels. None of these changes occured in gluean-F or saline treated rats. O n l y 0,0% of g lucan-P t rea ted rats s u r v i v e d 30 days whereas 100% of g lucan-F and sal ine t r e a t e d rats s u r v i v e d . We conclude that g lucan-P , in con t ras t to g l ucan -F , signif icantly h e i g h t e n s RES f u n c t i o n and t h a t t h i s e f f e c t is r e s p o n s i b l e f o r t h e LPS s e n s i t i v i t y . I n c r e a s e d amounts of in f lammatory mediators re leased by an expanded and h y p e r f u n c t i o n a l RES induce pa thophys i o l og i c changes which c o n t r i b u t e to the obse rved mortal i ty .

ROLE OF NEUTROPHILS IN PROTECTION AGAINST ESCHERICHIA COLI INDUCED PERITONITIS. David L. Williams, William Browder and Nicholas R. Dr Luzio. Departments of Physiology and Surgery, Tulane University School of Medicine, New Orleans, La. 70112. Glucan, a potent biologic response modifier, has been shown to improve survival, decrease histopathology, suppress bacteremia and maintain macrophage phagocytic function in a murine model of ~ coli peritonitis. This study was designed to examine neutrophil, lymphocyte and monocyte populations in the peritoneal cavity and peripheral blood of glucan and control mice following ~coli challenge. ICR/Tex mice weEe given glucan IP (150 mg/kg) or dextrose on days 5--~ prior to IP E. coli (i x i0~). Glucan administered IP, prior to septic challenge, resulted i-6- a significant (p<O.05) increase in the number of total peritoneal leukocytes. Analysis of peritoneal leukocytes revealed that the increase in the number of peritoneal cells following glucan, was attributable to significant (p<O.05) increases in the nu~nber of neutrophils. Examination of peripheral blood revealed that IP administration of ~ coli resulted in leukopenia in control mice. In contrast, glucan significantly (p<0.O~- n~ased neutr~phil counts at I0 hrs. post- challenge in peripheral blood (17.2 x lOJcu/mm vs. 0.7 x I0 cu/mm). Examination of lymphocytes and monocytes in peripheral blood of glucan mice revealed significant (p<O.05) decreases in both cell populations at 2, 4 and 6 hrs. post-challenge. We conclude that: l)peripheral blood neutrophils are increased in glucan-treated mice following ~coli challenge; 2) peritoneal neutrophil levels are maintained in glucan-treated mlce~6-~;-~) both lymphocyte and monocyte populations decrease in control and glucan ,aice challenged with coli; and 4) the beneficial effect of glncan may be mediated by neutrophils as well as -- a--~vated macrophages.

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