Abnormal granulocyte functions in autoimmune disorders demonstrated by microcalorimetry

Heat production by polymorphonuclear granulocytes (PMN) was assayed in 14 patients suffering from diseases known to be associated with circulating immune complexes (CIC) and in 10 healthy blood donors. The patients' PMN produced significantly more heat than the normal PMN when the cells were suspended in autologous plasma (23.8 +/- 3.9 pW/cell vs. 18.1 +/- 1.9 pW/cell, p less than 0.0005), but not when the cells were suspended in tissue culture medium (5.6 +/- 1.2 pW/cell vs. 5.6 +/- 0.8 pW/cell, p greater than 0.05). After mixing with IgG-coated latex particles the heat production by patients' PMN were significantly less stimulated than that of normal PMN when the cells were suspended in autologous plasma (42 +/- 13% vs. 75 +/- 22%, p less than 0.0005), but not when the cells were suspended in tissue culture medium (82 +/- 24% vs. 83 +/- 22%, p greater than 0.05). The increase of heat production by normal PMN after stimulation with IgG-coated latex particles was significantly lower when the cells were preincubated with heat aggregated human gammaglobulin compared to that obtained when the cells were preincubated in saline (11 +/- 10% vs. 51 +/- 11%, p less than 0.001). This finding shows that the increased PMN heat production which occurs after binding of the IgG-coated particles is mediated via Fc receptors. A plasma factor(s), possibly circulating immune complexes, can explain the abnormal PMN functions in the patients.