RNA transcripts for I-J polypeptides are apparently not encoded between the I-A and I-E subregions of the murine major histocompatibility complex.

Abstract

The I-J subregion of the mouse major histocompatibility complex has been reported to encode antigenic determinants expressed by suppressor T cells. Previously, cosmid clones were obtained from mouse sperm DNA that contain all of the sequences between the I-A and I-E subregions, where I-J has been mapped genetically. However, hybridization of these sequences to RNA prepared from several I-J-positive suppressor T-cell hybridomas did not reveal the presence of a transcript. In addition, no rearrangements in this DNA were detected in the suppressor T cells that we have analyzed. Our results indicate that the I-J polypeptides are not encoded between the I-A and I-E subregions of the major histocompatibility complex. We discuss several hypotheses concerning the possible location and expression of I-J genes.

T cell surface I-J glycoprotein. Concerted action of chromosome-4 and -17 genes forms an epitope dependent on alpha-D-mannosyl residues.

“…T suppressor cell lines did not yield /-region hybridizing mRNA (28). However, I-J k expression is cell cycle dependent (19); nonsynchronous cells were used and I-J k molecule synthesis was not demonstrated at the time of mRNA extraction (28). Finally, E~ or E~ polypeptide molecular weights do not match reported I-J k polypeptide weights (40,(43)(44)(45)(46).…”

“…Considerable debate has recently focused on the placement of the enigmatic I-J suppressor determinant controlling gene (4,27,28). Previous experiments (7), to express I-J k specificities can be attributed to its background genes, rather than to an inappro- priate H-2 k gene.…”

“…Furthermore, if the I-Jk-bearing structure were a receptor binding to E~ or E¢ chains (see below) both I-E and I-J determinants could be closely associated, as these studies indicate, but not part of the same polypeptide; conditions that would dissociate noncovalently bound polypeptides were not used. T suppressor cell lines did not yield /-region hybridizing mRNA (28). However, I-J k expression is cell cycle dependent (19); nonsynchronous cells were used and I-J k molecule synthesis was not demonstrated at the time of mRNA extraction (28).…”

B29: a member of the immunoglobulin gene superfamily exclusively expressed on beta-lineage cells.

“…When analyzed by the PROFILE method (12), the immunoglobulin-like domain of B29 also was related to other superfamily members including the V regions of T (18) and myeloma cell line S107A represent terminally differentiated immunoglobulin-secreting plasma cells (19). T-cell lines screened include T-cell lymphomas BW5147 and R1.1 (17), a helper T cell, EL4 (20); a helper T-cell hybridoma, AODK10.4 (21); suppressor T-cell hybridomas TS6, 7C, and VL3 (22); and a cytotoxic T-cell line, MD 90 (23 Genomic Library Screening. The B29 genomic clone was isolated from a BALB/c sperm library in A Charon 4A.…”

Cytokine Mimicry with an Immunologic Reformation: The Discovery of a Decade

“…By 1990, immune suppression as a mechanism had come into some doubt (22). With the discovery of IL-10 as a new suppressive cytokine, these authors helped to provide a solid framework for negative feedback mechanisms in T cell biology.…”