Nature of T lymphocyte recognition of macrophage-associated antigens. V. Contribution of individual peptide residues of human fibrinopeptide B to T lymphocyte responses.

Abstract

Guinea pig T lymphocyte responses to a decapeptide antigen (NH1-Asp5-Ans6-Glu7-Glu8-Gly9-Phe10-Phe11-Ser12-Ala13-Arg14-OH) of human fibrinopeptide B (hFPB) were examined using various synthetic peptide analogues containing single residue substitutions. Each analogue was examined for antigenicity as determined by an in vitro proliferative responses of hFPN-immune strain 2 guinae pig T cells. In addition, both strain 2 and strain 13 animals were immunized with each analogue and immunogenicity assessed by in vitro T cell-proliferative responses with the homologous immunizing analogue and the parent peptide. Replacement of arginine14 with lysine formed an immunogenic analogue which showed no antigenic cross-reactivity with the native peptide in strain 2 T cell responses. In addition, substitution of arginine14 with blocked lysine again produced a unique immunogenic analogue that showed little or no antigenic identity with the intact lysine analogue or the native peptide. In similar fashion, substitution of resideu phenylalanie10 with tyrosine or Phe(4-NO2) created unique immunogenic analogues with little or no antigenic identity to the native peptide with strain 2 T cells. By contrast, replacement of phenylalanine11 with either tyrosine or Phe(4-NO2) resulted in analogues with a total loss of immunogenicity and antigenicity in strain 2 T cell responses. An analogue in which glutamic acid7,8 were replaced with glutamine retained a small degree of antigenicity with hFPB-immune T cells, but T cells from strain 2 animals immunized with the Gln analogue responded only marginally to the Gln analogue while producing good proliferative responses with the native peptide. On the other hand, an analogue in which asparatic acid5 was replaced with asparagine retained most of the antigenic identity with hFPB for strain 2 T cell responses. None of thee analogues were immunogenic for strain 13 guinea pigs. These observations are discussed with respect to the contribution of each substituted residue to T cell respones, mechanism of Ir gene function, and a model for T cell recognition of small peptide antigens.

T-Lymphocyte Recognition of Antigen in Association with Gene Products of the Major Histocompatibility Complex

“…A review of the literature suggests not. A number of examples exist of experimental results that have as a possible interpretation a two subsite structure of the antigenic determinant recognized by T cells (32)(33)(34)(35)(36)(37). The oldest example is the classic Ir gene experiment of Levine, Ojeda & Benacerraf from 1963 (32).…”

T lymphocyte recognition of peptide antigens: evidence favoring the formation of neoantigenic determinants.

“…This is particularly interesting as both peptides are symmetrical with respect to the Phe residues in positions 10 and 11 in Bf17-14. We previously (4) found that Phe 1°, as well as Arg TM, contributed to the clonal specificity of T cell responses to Bf17-14, whereas substitutions for Phe 11 eliminated antigenicity and immunogenicity and substitutions for Gly 7 and Glu 8 altered immunogenicity but not the specificity of the response. Thus, the major differences between these two peptides as far as T cell responses are concerned are the changes of Ala 13 and Arg TM in Bfl7-14 to Glu.…”

“…whose sequences are shown in Fig. l, were synthesized and purified as described previously (4). Purified protein derivative of tuberculin (PPD) was purchased from Connaught Medical Research Laboratory, Willowdale, Ontario, Canada.…”

“…[2][3][4][5][6] wk after immunization with 400 #g of each peptide antigen in complete Freund's adjuvant (Difco Laboratories, Detroit, MI) guinea pigs was injected intraperitoneally with 25 ml of sterile mineral oil (Marcol 52; Exxon Corp., Linden, N J), and the resulting peritoneal exudate was harvested 3-4 d later. A T lymphocyte-enriched peritoneal exudate lymphocyte (PEL) population was prepared by passing cells over a rayon wool adherence column (6).…”

Possible Involvement of Transglutaminase in Endocytosis and Antigen Presentation

“…Spleens were teased and passed through stainless steel meshes in HBSS, and treated with Gey's hemolytic solution (8) for 2 min at 4 C to remove erythrocytes. Dead cells were removed by Ficoll-Metrizoate gradient (22) [12 parts of 14% (w/v) Ficoll in distilled water and five parts of 32 …”