ABSTRACT
The studies reported here were designed to determine whether sera from various patients could prevent neutrophils from responding to the lymphokine, neutrophil migration inhibition factor from T lymphocytes (NIF-T). Neutrophils from healthy donors were treated with sera from 84 subjects and assayed for responses to NIF-T. Serum from 7 of 37 patients (19%) with rheumatoid arthritis, systemic lupus erythematosus, and various forms of vasculitis showed blocking activity. In contrast, none of 47 subjects, including healthy individuals and patients with spondylarthropathies, cancer, and active infections had a serum factor that prevented neutrophils from responding to NIF-T (P less than 0.01). Serum blocking activity occurred transiently in association with infection by Staphylococcus aureus in one patient with rheumatoid arthritis. Moreover, autologous neutrophils from this same patient showed impaired responses to NIF-T. Blocking activity could be eluted from protein A-Sepharose in three of three patients studied. In three of seven patients, blocking activity was detected in serum cryoprecipitates, with a recovery of 46 to 78% of the blocking activity and overall enrichment (purification) of 137- to 281-fold. Analysis of cryoprecipitates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the predominance of immunoglobulins M and G. In one patient, the serum blocking activity was not cryoprecipitable, and cryoprecipitates from a patient with essential cryoglobulinemia failed to prevent neutrophils from responding to NIF-T. Blocking activity was relatively specific for NIF-T, as there was no effect on F-met-leu-phe-induced chemotaxis of neutrophils. Serum blocking activity in patients with connective tissue disease showed some correlation (r = 0.50; P less than 0.01) with immune complexes detected by polyethylene glycol precipitation but not Clq binding. These studies suggest that the response of neutrophils to NIF-T may be blocked by serum, possibly as a result of immune complexes or autoantibodies found primarily in patients with connective tissue disease.
