scholarly journals Thymic selection and thymic major histocompatibility complex class II expression are abnormal in mice undergoing graft-versus-host reactions.

1993 ◽  
Vol 178 (3) ◽  
pp. 805-814 ◽  
Author(s):  
J Desbarats ◽  
W S Lapp
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Negative Selection ◽  
Class Ii ◽  
Lymphoid Cells ◽  
Thymic Selection ◽  
Major Histocompatibility ◽  
Color Flow ◽  
F1 Hybrid ◽  
Histocompatibility Complex

The graft-vs.-host reaction (GVHR) results in damage to the epithelial and lymphoid compartments of the thymus and thus in abnormal maturation and function of thymocytes in mice undergoing GVHR. In this report, the effects of GVHR on thymic T cell receptor (TCR) expression and usage have been investigated. GVHR was induced in unirradiated F1 hybrid mice by the intravenous transfer of parental lymphoid cells. Expression of the CD3/TCR complex on thymocyte subsets defined by CD4 and CD8 was studied by three-color flow cytometry. The level of CD3/TCR was decreased on CD4+CD8-, but not CD4-CD8+, mature thymocytes. The lack of upregulation of CD3/TCR on CD4 single-positive thymocytes, but not on their CD8+ counterparts, suggested an abnormality of class II major histocompatibility complex (MHC) expression in the thymuses of mice undergoing GVHR. Immunofluorescence staining of thymic frozen sections revealed that MHC class II expression was dramatically decreased in GVH-reactive mice. GVHR-induced changes in positive and negative selection were evaluated by determining the incidence of specific V beta TCR segment usage in the thymus. In normal mice, thymocyte usage of any given V beta segment was highly consistent between individuals of the same strain and age; however, a marked divergence in the incidence of TCR V beta 6hi and V beta 8hi cells between GVH-reactive littermate mice was observed, suggesting that thymic positive selection had become disregulated in these animals. Furthermore, negative selection was defective; the incidence of phenotypically self-reactive V beta 6hi T cells was significantly greater in the thymuses of GVH-reactive mice bearing the endogenous superantigen Mls-1a than in untreated controls. Thus, mice undergoing GVHR showed defective TCR upregulation on CD4+CD8- thymocytes and changes in TCR usage reflecting aberrant thymic selection, in conjunction with decreased expression of MHC class II. Most abnormalities of TCR expression and usage on CD4+ thymocytes observed in GVH-reactive mice were analogous to those of class II knockout mice.

scholarly journals Relationship between invariant chain expression and major histocompatibility complex class II transport into early and late endocytic compartments.

1993 ◽  
Vol 177 (3) ◽  
pp. 583-596 ◽  
Author(s):  
P Romagnoli ◽  
C Layet ◽  
J Yewdell ◽  
O Bakke ◽  
R N Germain
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Endocytic Pathway ◽  
Invariant Chain ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Endocytic Compartments

Invariant chain (Ii), which associates with major histocompatibility complex (MHC) class II molecules in the endoplasmic reticulum, contains a targeting signal for transport to intracellular vesicles in the endocytic pathway. The characteristics of the target vesicles and the relationship between Ii structure and class II localization in distinct endosomal subcompartments have not been well defined. We demonstrate here that in transiently transfected COS cells expressing high levels of the p31 or p41 forms of Ii, uncleaved Ii is transported to and accumulates in transferrin-accessible (early) endosomes. Coexpressed MHC class II is also found in this same compartment. These early endosomes show altered morphology and a slower rate of content movement to later parts of the endocytic pathway. At more moderate levels of Ii expression, or after removal of a highly conserved region in the cytoplasmic tail of Ii, coexpressed class II molecules are found primarily in vesicles with the characteristics of late endosomes/prelysosomes. The Ii chains in these late endocytic vesicles have undergone proteolytic cleavage in the lumenal region postulated to control MHC class II peptide binding. These data indicate that the association of class II with Ii results in initial movement to early endosomes. At high levels of Ii expression, egress to later endocytic compartments is delayed and class II-Ii complexes accumulate together with endocytosed material. At lower levels of Ii expression, class II-Ii complexes are found primarily in late endosomes/prelysosomes. These data provide evidence that the route of class II transport to the site of antigen processing and loading involves movement through early endosomes to late endosomes/prelysosomes. Our results also reveal an unexpected ability of intact Ii to modify the structure and function of the early endosomal compartment, which may play a role in regulating this processing pathway.

scholarly journals CD1 and Major Histocompatibility Complex II Molecules Follow a Different Course during Dendritic Cell Maturation

2003 ◽  
Vol 14 (8) ◽  
pp. 3378-3388 ◽  
Author(s):  
Nicole N. van der Wel ◽  
Masahiko Sugita ◽  
Donna M. Fluitsma ◽  
Xaiochun Cao ◽  
Gerty Schreibelt ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
Dendritic Cell ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Dendritic Cell Maturation ◽  
Cell Maturation ◽  
Major Histocompatibility ◽  
Mhc Molecules ◽  
Histocompatibility Complex

The maturation of dendritic cells is accompanied by the redistribution of major histocompatibility complex (MHC) class II molecules from the lysosomal MHC class II compartment to the plasma membrane to mediate presentation of peptide antigens. Besides MHC molecules, dendritic cells also express CD1 molecules that mediate presentation of lipid antigens. Herein, we show that in human monocyte-derived dendritic cells, unlike MHC class II, the steady-state distribution of lysosomal CD1b and CD1c isoforms was unperturbed in response to lipopolysaccharide-induced maturation. However, the lysosomes in these cells underwent a dramatic reorganization into electron dense tubules with altered lysosomal protein composition. These structures matured into novel and morphologically unique compartments, here termed mature dendritic cell lysosomes (MDL). Furthermore, we show that upon activation mature dendritic cells do not lose their ability of efficient clathrin-mediated endocytosis as demonstrated for CD1b and transferrin receptor molecules. Thus, the constitutive endocytosis of CD1b molecules and the differential sorting of MHC class II from lysosomes separate peptide- and lipid antigen-presenting molecules during dendritic cell maturation.

scholarly journals MPYS, a Novel Membrane Tetraspanner, Is Associated with Major Histocompatibility Complex Class II and Mediates Transduction of Apoptotic Signals

2008 ◽  
Vol 28 (16) ◽  
pp. 5014-5026 ◽  
Author(s):  
Lei Jin ◽  
Paul M. Waterman ◽  
Karen R. Jonscher ◽  
Cindy M. Short ◽  
Nichole A. Reisdorph ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Cell Activation ◽  
Cytoplasmic Tail ◽  
Class Ii ◽  
Antigenic Peptides ◽  
Major Histocompatibility ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Death Signals

ABSTRACT Although the best-defined function of type II major histocompatibility complex (MHC-II) is presentation of antigenic peptides to T lymphocytes, these molecules can also transduce signals leading alternatively to cell activation or apoptotic death. MHC-II is a heterodimer of two transmembrane proteins, each containing a short cytoplasmic tail that is dispensable for transduction of death signals. This suggests the function of an undefined MHC-II-associated transducer in signaling the death response. Here we describe a novel plasma membrane tetraspanner (MPYS) that is associated with MHC-II and mediates its transduction of death signals. MPYS is unusual among tetraspanners in containing an extended C-terminal cytoplasmic tail (∼140 amino acids) with multiple embedded signaling motifs. MPYS is tyrosine phosphorylated upon MHC-II aggregation and associates with inositol lipid and tyrosine phosphatases. Finally, MHC class II-mediated cell death signaling requires MPYS-dependent activation of the extracellular signal-regulated kinase signaling pathway.

scholarly journals Engagement of major histocompatibility complex class II molecules by superantigen induces inflammatory cytokine gene expression in human rheumatoid fibroblast-like synoviocytes.

1992 ◽  
Vol 175 (2) ◽  
pp. 613-616 ◽  
Author(s):  
W Mourad ◽  
K Mehindate ◽  
T J Schall ◽  
S R McColl
Keyword(s):  
Gene Expression ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Inflammatory Cytokine ◽  
Class Ii ◽  
Type B ◽  
Major Histocompatibility ◽  
Ifn Gamma ◽  
Histocompatibility Complex ◽  
Mhc Class Ii Molecules

Cells in the rheumatoid synovium express high levels of major histocompatibility complex (MHC) class II molecules in vivo. We have therefore examined the ability of engagement of MHC class II molecules by the superantigen Staphylococcal enterotoxin A (SEA) to activate interleukin 6 (IL-6) and IL-8 gene expression in type B synoviocytes isolated from patients with rheumatoid arthritis. SEA had a minimal or undetectable effect on the expression of either gene in resting synoviocytes, as determined by Northern blot and specific enzyme-linked immunosorbent assay. However, induction of MHC class II molecule expression after treatment of synoviocytes with interferon gamma (IFN-gamma) enabled the cells to respond to SEA in a dose-dependent manner, resulting in an increase in both the level of steady-state mRNA for IL-6 and IL-8, and the release of these cytokines into the supernatant. IFN-gamma by itself had no effect on the expression of either cytokine. Pretreatment of the cells with the transcription inhibitor actinomycin D prevented the increase in cytokine mRNA induced by SEA, whereas cycloheximide superinduced mRNA for both cytokines after stimulation by SEA. Taken together, these results indicate that signaling through MHC class II molecules may represent a novel mechanism by which inflammatory cytokine production is regulated in type B rheumatoid synoviocytes, and potentially provides insight into the manner by which superantigens may initiate and/or propagate autoimmune diseases.

scholarly journals Major histocompatibility complex-restricted recognition of retroviral superantigens by V beta 17+ T cells.

1992 ◽  
Vol 176 (1) ◽  
pp. 275-280 ◽  
Author(s):  
M A Blackman ◽  
F E Lund ◽  
S Surman ◽  
R B Corley ◽  
D L Woodland
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Major Histocompatibility ◽  
Direct Role ◽  
Histocompatibility Complex ◽  
Class Ii Mhc ◽  
Mhc Class Ii Molecules

It has been established that at least some V beta 17+ T cells interact with an endogenous superantigen encoded by the murine retrovirus, Mtv-9. To analyze the role of major histocompatibility complex (MHC) class II molecules in presenting the Mtv-9 encoded superantigen, vSAG-9 to V beta 17+ hybridomas, a panel of nine hybridomas was tested for their ability to respond to A20/2J (H-2d) and LBK (H-2a) cells which had been transfected with the vSAG-9 gene. Whereas some of the hybridomas recognized vSAG-9 exclusively in the context of H-2a, other hybridomas recognized vSAG-9 exclusively in the context of H-2d or in the context of both H-2d and H-2a. These results suggest that: (a) the class II MHC molecule plays a direct role in the recognition of retroviral superantigen by T cells, rather than serving simply as a platform for presentation; and, (b) it is likely that components of the TCR other than V beta are involved in the vSAG-9/TCR/class II interaction.

scholarly journals Defective major histocompatibility complex class II assembly, transport, peptide acquisition, and CD4+ T cell selection in mice lacking invariant chain expression.

1993 ◽  
Vol 177 (6) ◽  
pp. 1699-1712 ◽  
Author(s):  
E K Bikoff ◽  
L Y Huang ◽  
V Episkopou ◽  
J van Meerwijk ◽  
R N Germain ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Critical Role ◽  
Class Ii ◽  
Intact Protein ◽  
Invariant Chain ◽  
Major Histocompatibility ◽  
Protein Antigens ◽  
Histocompatibility Complex ◽  
Class Ii Alpha

We used gene targeting techniques to produce mice lacking the invariant chain associated with major histocompatibility complex (MHC) class II molecules. Cells from these mice show a dramatic reduction in surface class II, resulting from both defective association of class II alpha and beta chains and markedly decreased post-Golgi transport. The few class II alpha/beta heterodimers reaching the cell surface behave as if empty or occupied by an easily displaced peptide, and display a distinct structure. Mutant spleen cells are defective in their ability to present intact protein antigens, but stimulate enhanced responses in the presence of peptides. These mutant mice have greatly reduced numbers of thymic and peripheral CD4+ T cells. Overall, this striking phenotype establishes that the invariant chain plays a critical role in regulating MHC class II expression and function in the intact animal.

scholarly journals Major histocompatibility complex class II+B7-1+ tumor cells are potent vaccines for stimulating tumor rejection in tumor-bearing mice.

1995 ◽  
Vol 181 (2) ◽  
pp. 619-629 ◽  
Author(s):  
S Baskar ◽  
L Glimcher ◽  
N Nabavi ◽  
R T Jones ◽  
S Ostrand-Rosenberg
Keyword(s):  
Major Histocompatibility Complex ◽  
Tumor Cells ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Genetically Engineered ◽  
Tumor Rejection ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Cell Immunity ◽  
Sarcoma Cells

Mice carrying large established major histocompatibility complex (MHC) class 1+ sarcoma tumors can be successfully treated by immunization with genetically engineered sarcoma cells transfected with syngeneic MHC class II plus B7-1 genes. This approach is significantly more effective than previously described strategies using cytokine- or B7-transduced tumor cells which are only effective against smaller tumor loads, and which cannot mediate regression of longer-term established tumors. The most efficient tumor rejection occurs if both the class II and B7-1 molecules are coexpressed on the same tumor cell. Immunity induced by immunization with class II+B7-1(+)-transfected sarcoma cells involves CD4+ and CD8+ T cells, suggesting that the increased effectiveness of the transfectants is due to their ability to activate both of these T cell populations.

scholarly journals Degradation of Mouse Invariant Chain: Roles of Cathepsins S and D and the Influence of Major Histocompatibility Complex Polymorphism

1997 ◽  
Vol 186 (4) ◽  
pp. 549-560 ◽  
Author(s):  
José A. Villadangos ◽  
Richard J. Riese ◽  
Christoph Peters ◽  
Harold A. Chapman ◽  
Hidde L. Ploegh
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Cysteine Proteases ◽  
Class Ii ◽  
Invariant Chain ◽  
Antigenic Peptides ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Antigen Presenting ◽  
Endocytic Compartments

Antigen-presenting cells (APC) degrade endocytosed antigens into peptides that are bound and presented to T cells by major histocompatibility complex (MHC) class II molecules. Class II molecules are delivered to endocytic compartments by the class II accessory molecule invariant chain (Ii), which itself must be eliminated to allow peptide binding. The cellular location of Ii degradation, as well as the enzymology of this event, are important in determining the sets of antigenic peptides that will bind to class II molecules. Here, we show that the cysteine protease cathepsin S acts in a concerted fashion with other cysteine and noncysteine proteases to degrade mouse Ii in a stepwise fashion. Inactivation of cysteine proteases results in incomplete degradation of Ii, but the extent to which peptide loading is blocked by such treatment varies widely among MHC class II allelic products. These observations suggest that, first, class II molecules associated with larger Ii remnants can be converted efficiently to class II–peptide complexes and, second, that most class II–associated peptides can still be generated in cells treated with inhibitors of cysteine proteases. Surprisingly, maturation of MHC class II in mice deficient in cathepsin D is unaffected, showing that this major aspartyl protease is not involved in degradation of Ii or in generation of the bulk of antigenic peptides.

scholarly journals Invariant chain and DM edit self-peptide presentation by major histocompatibility complex (MHC) class II molecules.

1996 ◽  
Vol 184 (5) ◽  
pp. 1747-1753 ◽  
Author(s):  
J F Katz ◽  
C Stebbins ◽  
E Appella ◽  
A J Sant
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Binding Pocket ◽  
Surface Expression ◽  
Class Ii ◽  
Invariant Chain ◽  
Generalized Function ◽  
Major Histocompatibility ◽  
Histocompatibility Complex

We have studied the consequences of invariant chain (Ii) and DM expression on major histocompatibility complex (MHC) class II function. Ii has a number of discrete functions in the biology of class II, including competitive blocking of peptide binding in the endoplasmic reticulum and enhancing localization in the endocytic compartments. DM is thought to act primarily in endosomes to promote dissociation of the Ii-derived (CLIP) peptide from the class II antigen-binding pocket and subsequent peptide loading. In this study, we have evaluated the functional role of Ii and DM by examining their impact on surface expression of epitopes recognized by a large panel of alloreactive T cells. We find most epitopes studied are influenced by both Ii and DM. Most strikingly, we find that surface expression of a significant fraction of peptide-class II complexes is extinguished, rather than enhanced, by DM expression within the APC. The epitopes antagonized by DM do not appear to be specific for CLIP. Finally, we found that DM was also able to extinguish recognition of a defined peptide derived from the internally synthesized H-2Ld protein. Thus, rather than primarily serving in the removal of CLIP, DM may have a more generalized function of editing the array of peptides that are presented by class II. This editing can be either positive or negative, suggesting that DM plays a specifying role in the display of peptides presented to CD4 T cells.

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