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Iodine and the Body

 

Iodine and the Immune System

 

SBARRA

 

Mycoplasmacidal activity of peroxidase-H2O2-halide systems.

Jacobs AA, Low IE, Paul BB, Strauss RR, Sbarra AJ.

Infect Immun. 1972 Jan;5(1):127-31.

 

"A mycoplasmacidal system consisting of myeloperoxidase (MPO)-containing granules, H2O2, and a halide is described. In all parameters measured, it appears to be identical to the MPO-H2O2-halide bactericidal system previously reported. It has a pH optimum of approximately 5.5 and an optimal MPO:H2O2 ratio of 1:25. The halide requirement can be satisfied by either chloride or iodide. Through the use of taurine or horseradish peroxidase substitution, chloride-mediated killing can be distinguished from iodide-mediated killing. The relationship of this mycoplasmacidal system to other mycoplasmacidal systems and to host surveillance of mycoplasma is discussed."

 

 

Role of the Phagocyte in Host-Parasite Interactions XXVII. Myeloperoxidase-H(2)O(2)-Cl-Mediated Aldehyde Formation and Its Relationship to Antimicrobial Activity.

Strauss RR, Paul BB, Jacobs AA, Sbarra AJ.

Infect Immun. 1971 Apr;3(4):595-602.

 

"Evidence is presented which suggests that the mechanism of action of the myeloperoxidase-H2O2-Cl(-) antimicrobial system in the phagocyte is by the formation of aldehydes. Aldehyde production resulting from myeloperoxidase-mediated decarboxylation and deamination of alanine was quantitated with 20,000-g granules from guinea pig polymorphonuclear leukocytes serving as the enzyme. Equimolar quantities of acetaldehyde and CO2 were obtained. There was an absolute requirement for both H2O2 and Cl(-) for decarboxylation by the myeloperoxidase-containing granules. The myeloperoxidase-H202-Cl(-) system decarboxylated both d- or l-alanine equally and had a pH optimum of 5.3. Decarboxylation of l-alanine by intact guinea pig polymorphonuclear leukocytes was increased 2.5-fold by phagocytosis. Guaiacol peroxidation by the granules was inhibited 90% in the presence of Cl(-) at acid pH. Under these conditions, decarboxylation and deamination of amino acids by myeloperoxidase were significantly stimulated, resulting in aldehyde production. Taurine, a competitive inhibitor of amino acid decarboxylation, inhibited bactericidal activity of the myeloperoxidase-H2O2-Chloride system but had no effect on the myeloperoxidase-H2O2-Iodide bactericidal system. Since the myeloperoxidase-H202-Iodide system does not participate in amino acid decarboxylation, its mechanism of antimicrobial action appears to be different from that found with Chloride."

 

 

Role of the Phagocyte in Host-Parasite Interactions XXIV. Aldehyde Generation by the Myeloperoxidase-H202-Chloride Antimicrobial System: a Possible In Vivo Mechanism of Action.

Paul BB, Jacobs AA, Strauss RR, Sbarra AJ.

Infect Immun. 1970 Oct;2(4):414-418.

 

"Myeloperoxidase (MPO), H2O2, and chloride ions in the presence of bacteria form aldehydes and are bactericidal. The use of heat-inactivated MPO prevented both killing and aldehyde generation. Decarboxylation and deamination of carboxyl and amino group substrates arising from the bacterial surface may participate in the reaction which yields aldehydes. Bacterial contact was essential for killing. Decarboxylation and bactericidal activities were noted when physiological concentrations of chloride were used. When MPO was replaced with horseradish peroxidase (HPO) in the chloride medium, decarboxylation and bactericidal activities were no longer noted. In contrast, iodide functioned in the antimicrobial system with either MPO or HPO. The iodide concentrations required were at least sixfold greater than circulating blood iodide levels. Moreover, decarboxylation did not occur in the presence of iodide with either enzyme. Thus, both halides function in the MPO-H202 system but by different mechanisms. It is likely that in vivo under most conditions chloride is the functional halide and that generation of aldehydes is the mechanism responsible for the antimicrobial activity of the MPO-H202-chloride system."

 

 

Role of the Phagocyte in Host-Parasite Interactions XXIV. Aldehyde Generation by the Myeloperoxidase-H(2)O(2)-Chloride Antimicrobial System: a Possible In Vivo Mechanism of Action.

Paul BB, Jacobs AA, Strauss RR, Sbarra AJ

Infect Immun. 1970 Oct;2(4):414-418.

 

"Myeloperoxidase (MPO), H2O2, and chloride ions in the presence of bacteria form aldehydes and are bactericidal. The use of heat-inactivated MPO prevented both killing and aldehyde generation. Decarboxylation and deamination of carboxyl and amino group substrates arising from the bacterial surface may participate in the reaction which yields aldehydes. Bacterial contact was essential for killing. Decarboxylation and bactericidal activities were noted when physiological concentrations of chloride were used. When MPO was replaced with horseradish peroxidase (HPO) in the chloride medium, decarboxylation and bactericidal activities were no longer noted. In contrast, iodide functioned in the antimicrobial system with either MPO or HPO. The iodide concentrations required were at least sixfold greater than circulating blood iodide levels. Moreover, decarboxylation did not occur in the presence of iodide with either enzyme. Thus, both halides function in the MPO-H2O2 system but by different mechanisms. It is likely that in vivo under most conditions chloride is the functional halide and that generation of aldehydes is the mechanism responsible for the antimicrobial activity of the MPO-H2O2-chloride system."

 

 

Role of the phagocyte in host-parasite interactions. XII. Hydrogen peroxide-myeloperoxidase bactericidal system in the phagocyte.

McRipley RJ, Sbarra AJ.

J Bacteriol. 1967 Nov;94(5):1425-30.

 

"An antimicrobial system in polymorphonuclear neutrophils (PMN) consisting of myeloperoxidase and hydrogen peroxide has been proposed. This system appears to be activated during phagocytosis as a result of the stimulated metabolic activities. A lysed-granules (LG) fraction was prepared from guinea pig exudative PMN. LG alone possessed bactericidal activity which was related to the pH of the reaction; the lower the pH, the more marked the activity. When low concentrations of both H2O2 and LG were combined under conditions where neither factor alone exhibited significant killing power, there was a striking increase in bactericidal activity. This enhanced activity was much greater than an additive effect. The LG-peroxide antibacterial system was most active over a pH range of 4.0 to 6.0. The activity of the LG-peroxide system was essentially abolished by peroxidase inhibitors, NaN3, KCN, and aminotriazole. The antibacterial activity of this system was nonspecific in nature, being equally effective against gram-negative and gram-positive organisms."

 

 
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