The pore-forming protein (perforin) of cytolytic T lymphocytes is immunologically related to the components of membrane attack complex of complement through cysteine-rich domains.

J D Young,C C Liu,L G Leong,Z A Cohn

doi:10.1084/jem.164.6.2077

Abstract

Structural, functional and immunological similarities between the ninth component of complement (C9) and the lymphocyte pore-forming protein (PFP, perforin) have recently been described (8-10). PFP is shown here to be immunologically related to all other components of the membrane attack complex (MAC) of human complement, namely, C5b-6, C7, C8, and C9. Polyclonal antibodies raised against purified human C5b-6, C7, C8, or C9 react with other components of the MAC and with mouse lymphocyte PFP. The antigenic epitopes shared by human complement proteins and mouse lymphocyte PFP are limited to cysteine-rich domains. Only complement proteins that have been reduced and alkylated elicit the production of crossreactive antibodies when used as immunogens. The nonreduced forms of complement components or lymphocyte PFP neither react with these antibodies nor give rise to crossreactive antibodies. The homologous domains of complement proteins and lymphocyte PFP may play related functions in their attachment to lipid membranes and assembly of membrane lesions.

Highlights

PFP is shown here to be immunologically related to all other components of the membrane attack complex
The homologous domains of complement proteins and lymphocyte PFP may play related functions in their attachment to lipid membranes and assembly of membrane lesions

Summary

Materials and Methods

The homogeneity of purified C components was ascertained by SDS-gel electrophoresis Isolation of granules and PFP/perforin followed published procedure given elsewhere (16). Antisera against C5b-6, C7, C8, C9, and PFP/perforin were generated by following the multiple injections of antigens scheme outlined elsewhere 3R0edugu,cebdoialendd in 1 % SDS) into rabbits alkylated antigens were prepared as described (8). Immunoblots were developed using mini-gels (Model 360, Bio-Rad Laboratories, Richmond, CA) with gradient polyacrylamide of 4-20%, followed by electrotransfer of proteins to nitrocellulose membranes at a constant 400 mA for 2 .5 h (19). (St. Louis, MO) and for the blots consisted of prestained protein markers obtained from Bethesda Research Laboratories (Gaithersburg, MD)

Results

Discussion

Summary