ACTIVATION OF HUMAN-MONOCYTES BY BOTH HUMAN BETA-1H AND C3B

  • 1 January 1982
    • journal article
    • research article
    • Vol. 46  (2) , 307-312
Abstract
Highly purified human .beta.1H and complement component C3b, 2 proteins of the alternative pathway of C activation, were tested to determine if they could exert an influence on the activity of human monocytes (M.vphi.). The activation process of M.vphi. was assessed by measurements of the respiratory burst in terms of nitro blue tetrazolium (NBT) reduction and by chemiluminescence (CL) tests. In NBT reduction experiments, a tendency for .beta.1H to increase NBT reduction was found, whille C3b was found to be rather inhibitory. In CL measurements, both .beta.1H and C3b displayed a stimulatory effect on M.vphi., showing different time- and dose-dependency. For .beta.1H, the maximum stimulation occurred after 15 min; for C3b after 45 min. Zymosan particles which served as a positive control also showed the highest stimulation after 45 min. In dose-response experiments, .beta.1H reached a plateau ranging from 30-80 .mu.g/ml. Using C3b up to 170 .mu.g/ml, no plateau was reached. M.vphi.-depletion and enrichment studies suggested at M.vphi. as being responsible for the stimulatory effects found. The differences between NBT reduction and CL could possibly be explained by the measurement of only cell-bound reductive potentials by NBT reduction, while in CL measurements, products of the extracellular space are also assessed. Both human .beta.1H and C3b apparently are appropriate stimuli for human monocytes.

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