Lymphocyte chemotaxis in inflammation. IX. Further characterization of lymphocyte chemotactic lymphokines produced by purified protein derivative-stimulation in vitro and in vivo.

As recently reported, one lymphocyte chemotactic factor (beta-LCF, mol. wt. about 27,000) released from activated guinea-pig lymphocytes appeared to be identical to one of the LCFs (LCF-d) isolated from extract of purified protein derivative (PPD)-induced delayed-type hypersensitivity skin reaction sites in guinea-pigs with respect to antigenicity and chemotactic effect for T cells. However, the mol. wt. of LCF-d (about 300,000) was clearly distinct from beta-LCF. The experiments were undertaken to clarify the problem. beta-LCF appeared to be bound to some protein of normal guinea-pig serum (GPS) because the chemotactic activity was revealed in the fraction corresponding to that of LCF-d when the mixtures of beta-LCF with GPS were applied to a Sephadex G-200 column. Additionally, binding experiments using fluorescein isothiocyanate (FITC)-labelled beta-LCF were performed; fluorescence was only detected in the chemotactic fraction. It was thus assumed that the lymphokine (beta-LCF) would be released from activated lymphocytes around the inflammatory tissue, then bound with serum protein exuded in the site and function as LCF-d. The possibility was supported by the evidence that beta-LCF like-chemotactic substance (mol. wt. about 27,000) was dissociated from LCF-d under acid conditions. The factor dissociated from LCF-d was also bound with GPS protein under neutral conditions and converted to high molecular substance resembling LCF-d physiochemically. Furthermore, the chemotactic activity of LCF-d was almost completely absorbed by antibody against GPS. It is thus considered that the chemotactic activity of LCF-d may be attributed to beta-LCF released from activated lymphocytes and that some serum protein which binds beta-LCF may function as a carrier protein in the DTH sites.