Soluble FcγRIII levels in neutropenic patients who were followed longitudinally. Mean follow-up was 9.4 months (range, 1 to 17) in which at least two blood samples were tested (mean, 2.95; range, 2 to 5). Patients without infections were divided in two groups: one with sFcγRIII levels above 100 AU (○; n = 9) and one with sFcγRIII levels below 100 AU (□; n = 6). All patients with reported infections had sFcγRIII below 100 AU (▪; n = 6).