Metal content of neutrophil granules is altered in chronic inflammation.

The mass fraction of certain elements was measured in isolated granulocytes and isolated granulocyte granule fractions from patients with active inflammatory arthritides (N = 6) and healthy controls (N = 6). The patients had significantly increased amounts of Ca in the granulocytes, in the specific and light azurophil granules, but normal Ca amounts in the dense azurophil granules. Sr was below the detection limit in the granulocytes and granule fraction from controls, but it appeared in high concentrations in the granulocytes and all granule fractions from the patients. The patients had considerably increased granulocyte amounts of Mn but only slightly increased Mn concentrations in the specific granules. Mn was not detectable in azurophil granules from patients and controls. A prominent accumulation of Fe was seen in the granulocytes from the patients, together with an Fe accumulation in the specific granules. Fe was below the detection limit in azurophil granules from patients and controls. The patients had reduced granulocyte Zn and reduced amounts of Zn in the dense and light azurophil granules but normal Zn amounts in the specific granules. The results obtained indicate that the granulocyte accumulation of Ca, Sr, and Fe observed during chronic inflammation is associated with corresponding granule accumulation of these metals; the considerable Mn accumulation in granulocytes during inflammation is not localized in their granules; and the granule subpopulations differ in their capacity to store certain metals.