Dissolution of two Arsenic Compounds by Alveolar Macrophages

THE ABILITY OF RABBIT ALVEOLAR MACROPHAGES TO DISSOLVE TWO ARSENIC COMPOUNDS, 74AS-LABELLED LEAD ARSENATE AND ARSENIC TRISULFIDE, WAS STUDIED IN VITRO. THE SOLUBILITIES IN WATER OF THESE TWO COMPOUNDS ARE DIFFERENTLY RELATED TO PH. THE SOLUBILITY OF LEAD ARSENATE INCREASES AND THAT OF ARSENIC TRISULFIDE DECREASES WITH DECREASING PH. THE RADIOLABELLED PARTICLES WERE INCUBATED WITH AND WITHOUT MACROPHAGES FOR UP TO 3 DAYS, WHEREAFTER THE AMOUNT OF 74AS IN SOLUBLE FORM AND THE AMOUNT IN PARTICLE FORM AND/OR BOUND TO MACROPHAGES WAS DETERMINED. THE RESULTS STRONGLY SUPPORT THE HYPOTHESIS THAT THE DISSOLUTION OF PARTICLES BY MACROPHAGES IS INFLUENCED BY THE ACID MILIEU IN THE PHAGOSOMES. ABOUT 14% OF THE 74AS-LABELLED LEAD ARSENATE PARTICLES INCUBATED FOR 3 DAYS WITH THE MACROPHAGES WAS RELEASED INTO THE CULTURE MEDIUM, COMPARED TO ABOUT 2% OF THE PARTICLES INCUBATED WITH THE CULTURE MEDIUM WITHOUT MACROPHAGES. WITH THE ARSENIC TRISULFIDE PARTICLES, LESS SOLUBLE 74AS WAS RELEASED INTO THE MEDIUM IN SAMPLES WITH MACROPHAGES THAN IN SAMPLES WITHOUT MACROPHAGES. THE RESULTS INDICATE THAT DISSOLUTION IN THE PHAGOSOMES OF THE MACROPHAGES IS OF GREAT IMPORTANCE FOR THE CLEARANCE OF PARTICLES, SUCH AS LEAD ARSENATE, WHICH ARE SOLUBLE AT PH 4 BUT ONLY VERY SLIGHTLY SOLUBLE AT PH 7. FOR PARTI- CLES LIKE ARSENIC TRISULFIDE, THE SOLUBILITY OF WHICH DECREASES WITH DECREA- SING PH, PHAGOCYTOSIS BY THE MACROPHAGES MAY INHIBIT CLEARANCE FROM THE LUNGS.

MARAFANTE Erminio;  LUNDBORG M.;  CAMNER P.; 

1995-03-15

JRC4203

https://publications.jrc.ec.europa.eu/repository/handle/JRC4203,