A soluble divalent class I major histocompatibility complex molecule inhibits alloreactive T cells at nanomolar concentrations.
Genetically engineered or chemically purified soluble monovalent major histocompatibility complex (MHC) molecules, which have previously been used to study T cells, have not blocked cytotoxic T-cell responses. Here we describe a genetically engineered divalent class I MHC molecule which inhibits lysis of target cells by alloreactive cytotoxic T cells. This protein, H-2Kb/IgG, was generated as a fusion protein between the extracellular domains of a murine class I polypeptide, H-2Kb, and an immunoglobulin heavy chain polypeptide. The chimeric protein has serological and biochemical characteristics of both the MHC and IgG polypeptides. Nanomolar concentrations of H-2Kb/IgG inhibited lysis of H-2Kb-expressing target cells not only by alloreactive H-2Kb-specific T-cell clones but also by alloreactive H-2Kb-specific primary T-cell cultures. A direct binding assay showed high-affinity binding between the H-2Kb/IgG molecule and an H-2Kb-specific alloreactive T-cell clone. Unlabeled H-2Kb/IgG displaced 125I-labeled H-2Kb/IgG from T cells with an IC50 of 1.2 nM.
Dal Porto
J
J
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224.
Johansen
T E
TE
Catipović
B
B
Parfiit
D J
DJ
Tuveson
D
D
Gether
U
U
Kozlowski
S
S
Fearon
D T
DT
Schneck
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D004305:Dose-Response Relationship, Drug; D005805:Genes, MHC Class I / Q000235:genetics / Q000276:immunology*; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D012995:Solubility; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D014162:Transfection
D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D011993:Recombinant Fusion Proteins