Abstract
The relationship between Fc receptor (FcR) function and activation of murine macrophage populations for non-specific tumor cytotoxicity was studied. Oil-elicited inflammatory peritoneal macrophages (PMФ) from C3HeB/FeJ mice had higher FcR function upon harvest than resident PMФ from the same strain or elicited PMФ from genetically deficient C3H/HeJ mice. C3HeB/FeJ inflammatory PMФ were uniformly responsive to activation by MAF and the complement activators: LPS, Poly I:C, cobra venom factor (CVF) and zymosan for tumoricidal activity. Resident cells from the same strain and C3H/HeJ-elicited PMФ were uniformly unresponsive to the same activators. In vitro culture of C3HeB/FeJ resident PMФ with fetal bovine serum for 24–48 h produced unregulation of FcR function which coincided with a conversion from an unresponsive to a responsive state for tumoricidal activity. Reconstitution of the FcR function of C3H/HeJ-elicited PM In vitro during 24–48 h culture with lymphokine or Poly I:C also coincided with the restoration of responsiveness to activation by LPS, CVF, and zymosan for tumor cytotoxicity. Thus, the consistent temporal relationship between upregulated FcR function and the capacity of macrophages to respond to activation for non-specific tumoricidal activity may be more than coincidental. Preincubation of responsive C3HeB/FeJ-elicited PMФ with insoluble immune complex or heat-aggregated IgG was shown to blockade FcR-mediated phagocytosis and to abrogate LPS-mediated tumoricidal activity. Interestingly, FcR blockade by IgG-opsonized sheep erythrocyte conjugates selectively inhibited activation by MAF, LPS, and Poly I:C, but had no inhibitory effect on activation by CVF or zymosan. Similar blockade of C3b receptors produced an identical pattern of selective inhibition of activation. This selective inhibition of non-specific tumoricidal activity by FcR/C3bR blockade suggests the existence of two pathways for antibodyindependent activation of macrophages.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
