The Chemotactic Activity of Normal and Complement-Activated Serum as Measured by the Leading-Front Method Using a Boyden Chamber

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Abstract
The chemotactic activity in [human] serum, defined as the attractant effect of serum on the migration of neutrophil granulocytes was investigated for the purpose of characterizing the major chemotactic factors in serum as measured by the leading-front technique, using a modified Boyden chamber. The chemotactic activity was measured in fresh and heated normal and activated serum and in serum fractions thereof separated by gel filtration. By gel filtration on Sephacryl S-200 a partly heat-labile C3[complement component 3]-C5-associated chemotactic factor with MW between 70,000-150,000 was isolated from fresh normal serum. The heat-labile chemotactic activity was destroyed by pronounced complement activation. Gel filtration of complement-activated serum on a Sephacryl S-200 column showed the existence of one C5-associated chemotactic factor with .apprx. 70,000 MW and one unidentified factor with .apprx. 150,000 MW whereas no low MW chemotactic activity was demonstrated. Gel filtration of activated serum on a Sephadex G-75 column demonstrated one C5-associated chemotactic factor of .apprx. 70,000 MW and one 10,000-50,000 MW factor active only in the presence of 2% normal serum. The chemotactic activity in fresh normal serum is probably mediated by a partly heat-labile C3-C5-associated complex. In activated serum 3 chemotactic factors were demonstrated, 1 unidentified factor with 150,000 MW and 2 C5-dependent factors with 70,000 and 10,000-50,000 MW, the latter probably corresponding to C5adesarg. C5a is not the only chemotactic factor generated in serum.