PRESENCE OF C5A-POTENTIATING ACTIVITY IN THE PLASMA OF A PATIENT WITHKIMURAS-DISEASE

To determine whether the response to the active complement fragment C5 a in polymorphonuclear leukocytes (PMN) obtained from a patient with K imura's disease is similar to that in normal subjects, we evaluated su peroxide anion (O-2(-))generation after stimulation with C5a. The pati ent's PMN produced more O-2(-) than did those from healthy controls af ter stimulation with human C5a in vitro. The response returned to norm al with the improvement in clinical indicators after initiation of ste roid administration. We conducted the following experiments with the p lasma of this patient during the active disease stage to establish the presence of a humoral factor that potentiated the C5a-response of PMN . Incubation of PMN from normal controls having the same blood type as the patient at 37 degrees C for 2h with the patient's plasma at the a ctive disease stage revealed that the cells generated abundant O-2(-) after stimulation with C5a. Incubation of normal PMN with the patient' s plasma during the inactive disease stage showed no potentiated respo nse to C5a. This activity was lost after incubation at 56 degrees C fo r 30 min. Coincubation of PMN with methylprednisolone up to 100 mu g/m l did not suppress this activity. Although the plasma concentration of C5a at the active stage was mildly elevated (13 ng/ml), it was below the limit of detection (<10 ng/ml) at the inactive stage. These result s suggest the presence of a heat-labile, humoral factor in the patient 's plasma that upregulated the response of PMN to C5a and that was not suppressed by in vitro treatment with a steroid. This factor may infl uence the acute inflammatory reaction in this disorder.