scholarly journals Major Histocompatibility Complex Class II Compartments in Human and Mouse B Lymphoblasts Represent Conventional Endocytic Compartments

1997 ◽  
Vol 139 (3) ◽  
pp. 639-649 ◽  
Author(s):  
Monique J. Kleijmeer ◽  
Stanislaw Morkowski ◽  
Janice M. Griffith ◽  
Alexander Y. Rudensky ◽  
Hans J. Geuze
Keyword(s):  
Major Histocompatibility Complex ◽  
B Cells ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Invariant Chain ◽  
Histocompatibility Complex ◽  
Peptide Complexes ◽  
Endocytic Compartments ◽  
Human And Mouse ◽  
Mhc Class Ii Molecules

In most human and mouse antigen-presenting cells, the majority of intracellular major histocompatibility complex (MHC) class II molecules resides in late endocytic MHC class II compartments (MIICs), thought to function in antigen processing and peptide loading. However, in mouse A20 B cells, early endocytic class II-containing vesicles (CIIVs) have been reported to contain most of the intracellular MHC class II molecules and have also been implicated in formation of MHC class II–peptide complexes. To address this discrepancy, we have studied in great detail the endocytic pathways of both a human (6H5.DM) and a mouse (A20.Ab) B cell line. Using quantitative immunoelectron microscopy on cryosections of cells that had been pulse–chased with transferrin-HRP or BSA-gold as endocytic tracers, we have identified up to six endocytic subcompartments including an early MIIC type enriched in invariant chain, suggesting that it serves as an important entrance to the endocytic pathway for newly synthesized MHC class II/invariant chain complexes. In addition, early MIICs represented the earliest endocytic compartment containing MHC class II– peptide complexes, as shown by using an antibody against an abundant endogenous class II–peptide complex. The early MIIC exhibited several though not all of the characteristics reported for the CIIV and was situated just downstream of early endosomes. We have not encountered any special class II-containing endocytic structures besides those normally present in nonantigen-presenting cells. Our results therefore suggest that B cells use conventional endocytic compartments rather than having developed a unique compartment to accomplish MHC class II presentation.

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 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 Distinct Intracellular Compartments Involved in Invariant Chain Degradation and Antigenic Peptide Loading of Major Histocompatibility Complex (MHC) Class II Molecules

1997 ◽  
Vol 139 (6) ◽  
pp. 1433-1446 ◽  
Author(s):  
Giorgio Ferrari ◽  
Andrew M. Knight ◽  
Colin Watts ◽  
Jean Pieters
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Human Leukocyte ◽  
Subcellular Location ◽  
Class Ii ◽  
Invariant Chain ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Peptide Loading ◽  
Mhc Class Ii Molecules

Major histocompatibility complex (MHC) class II molecules are transported to intracellular MHC class II compartments via a transient association with the invariant chain (Ii). After removal of the invariant chain, peptides can be loaded onto class II molecules, a process catalyzed by human leukocyte antigen-DM (HLA-DM) molecules. Here we show that MHC class II compartments consist of two physically and functionally distinct organelles. Newly synthesized MHC class II/Ii complexes were targeted to endocytic organelles lacking HLA-DM molecules, where Ii degradation occurred. From these organelles, class II molecules were transported to a distinct organelle containing HLA-DM, in which peptides were loaded onto class II molecules. This latter organelle was not directly accessible via fluid phase endocytosis, suggesting that it is not part of the endosomal pathway. Uptake via antigen-specific membrane immunoglobulin resulted however in small amounts of antigen in the HLA-DM positive organelles. From this peptide-loading compartment, class II–peptide complexes were transported to the plasma membrane, in part after transit through endocytic organelles. The existence of two separate compartments, one involved in Ii removal and the other functioning in HLA-DM–dependent peptide loading of class II molecules, may contribute to the efficiency of antigen presentation by the selective recruitment of peptide-receptive MHC class II molecules and HLA-DM to the same subcellular location.

scholarly journals The Formation of Immunogenic Major Histocompatibility Complex Class II–Peptide Ligands in Lysosomal Compartments of Dendritic Cells Is Regulated by Inflammatory Stimuli

2000 ◽  
Vol 191 (6) ◽  
pp. 927-936 ◽  
Author(s):  
Kayo Inaba ◽  
Shannon Turley ◽  
Tomonori Iyoda ◽  
Fumiya Yamaide ◽  
Susumu Shimoyama ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Late Endosomes ◽  
Inflammatory Stimuli ◽  
Peptide Complexes ◽  
Mhc Class Ii Molecules

During their final differentiation or maturation, dendritic cells (DCs) redistribute their major histocompatibility complex (MHC) class II products from intracellular compartments to the plasma membrane. Using cells arrested in the immature state, we now find that DCs also regulate the initial intracellular formation of immunogenic MHC class II–peptide complexes. Immature DCs internalize the protein antigen, hen egg lysozyme (HEL), into late endosomes and lysosomes rich in MHC class II molecules. There, despite extensive colocalization of HEL protein and MHC class II products, MHC class II–peptide complexes do not form unless the DCs are exposed to inflammatory mediators such as tumor necrosis factor α, CD40 ligand, or lipoplolysaccharide. The control of T cell receptor (TCR) ligand formation was observed using the C4H3 monoclonal antibody to detect MHC class II–HEL peptide complexes by flow cytometry and confocal microscopy, and with HEL-specific 3A9 transgenic T cells to detect downregulation of the TCR upon MHC–peptide encounter. Even the binding of preprocessed HEL peptide to MHC class II is blocked in immature DCs, including the formation of C4H3 epitope in MHC class II compartments, suggesting an arrest to antigen presentation at the peptide-loading step, rather than an enhanced degradation of MHC class II–peptide complexes at the cell surface, as described in previous work. Therefore, the capacity of late endosomes and lysosomes to produce MHC class II–peptide complexes can be strictly controlled during DC differentiation, helping to coordinate antigen acquisition and inflammatory stimuli with formation of TCR ligands. The increased ability of maturing DCs to load MHC class II molecules with antigenic cargo contributes to the >100-fold enhancement of the subsequent primary immune response observed when immature and mature DCs are compared as immune adjuvants in culture and in mice.

scholarly journals Biochemical evidence for the rapid assembly and disassembly of processed antigen-major histocompatibility complex class II complexes in acidic vesicles of B cells.

1992 ◽  
Vol 175 (2) ◽  
pp. 425-436 ◽  
Author(s):  
E W Marsh ◽  
D P Dalke ◽  
S K Pierce
Keyword(s):  
Major Histocompatibility Complex ◽  
B Cells ◽  
Cytochrome C ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Biochemical Evidence ◽  
Histocompatibility Complex ◽  
Acidic Vesicles ◽  
Acidic Vesicle ◽  
Mhc Class Ii Molecules

Helper T cell recognition of antigen requires that it be processed within antigen-presenting cells (APC) to peptide fragments that subsequently bind to major histocompatibility complex (MHC) class II molecules and are displayed on the APC surface. Heretofore, processed antigen-MHC class II complexes have been detected by functional assays, measuring the activation of specific T cells. We now report direct, biochemical evidence for the assembly of processed antigen-MHC class II complexes within splenic B cells as APC. The I-Ek MHC class II molecules were immunoprecipitated from B cells that had processed the model protein antigen cytochrome c radiolabeled across its entire length by reductive methylation of lysine residues and covalently coupled to Ig-specific antibodies, allowing internalization after binding to surface Ig. Our previous studies showed that I-Ek immunoaffinity purified from B cells that had processed cytochrome c contains functional processed antigen--MHC class II complexes and that approximately 0.2% of the I-Ek molecules are specifically associated with one of two predominant processed antigenic fragments. Here we show that these complexes are rapidly assembled, within 30-60 min after antigen binding to surface Ig on splenic B cells. Maximal numbers of complexes are assembled by 2 h in a process that is sensitive to acidic vesicle inhibitors but not to inhibitors of protein synthesis. The processed antigen-I-Ek complexes have a relatively short half-life of 2-4 h and are disassembled or degraded within 8 h after antigen is first internalized. The disassembly or degradation of the processed antigen-I-Ek complexes requires acidic vesicle function, and in the presence of an acidic vesicle inhibitor the complexes are long lived. Thus, using a biochemical assay to monitor processed antigen-I-Ek complexes, we find that, in B cells, processed antigen is relatively rapidly associated in acidic vesicles with preexisting MHC class II molecules, and the complexes are disassembled 4-6 h later in processes that also require acid vesicle function.

scholarly journals Major histocompatibility complex class II compartments in human B lymphoblastoid cells are distinct from early endosomes.

1995 ◽  
Vol 182 (2) ◽  
pp. 325-334 ◽  
Author(s):  
P J Peters ◽  
G Raposo ◽  
J J Neefjes ◽  
V Oorschot ◽  
R L Leijendekker ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Intracellular Distribution ◽  
Endocytic Pathway ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Early Endosomes ◽  
Endocytic Compartments ◽  
Mhc Class Ii Molecules

In human B lymphoblastoid cell lines, the majority of major histocompatibility complex (MHC) class II heterodimers are located on the cell surface and in endocytic compartments, while invariant chain (Ii)-associated class II molecules represent biosynthetic intermediates which are present mostly in the endoplasmic reticulum and Golgi complex. To investigate the origin of the MHC class II-positive compartments and their relation to early endosomes, the intracellular distribution of MHC class II molecules and Ii in relation to endocytic tracers was studied in human lymphoblastoid B cells by immunoelectronmicroscopy on ultrathin cryosections. Cross-linking of surface immunoglobulins, followed by a brief period of internalization of the immune complexes, did not alter the intracellular distribution of MHC class II molecules. While early endosomes were abundantly labeled for the cross-linked immunoglobulins, < 1% of total MHC class II molecules were detectable in early endosomes. MHC class II- and Ii-positive structures associated with the trans-Golgi network can be reached by endocytosed bovine serum albumin (BSA)-gold conjugates after 30 min of internalization. Prolonged exposure to BSA-gold allowed visualization of later endocytic compartments, in which a progressive loss of Ii was observed: first the lumenal portion, and then the cytoplasmic portion of Ii escaped detection, culminating in the formation of MHC class II-positive compartments (MIIC) devoid of Ii. The loss of Ii also correlated with a transition from a multivesicular to a multilaminar, electron-dense MIIC. The intracellular compartments in which class II molecules reside (MIIC) are therefore a heterogeneous set of structures, part of the later aspects of the endocytic pathway.

scholarly journals The CLIP region of invariant chain plays a critical role in regulating major histocompatibility complex class II folding, transport, and peptide occupancy.

1994 ◽  
Vol 180 (3) ◽  
pp. 1107-1113 ◽  
Author(s):  
P Romagnoli ◽  
R N Germain
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Peptide Binding ◽  
Class Ii ◽  
Class I ◽  
Structural Basis ◽  
Invariant Chain ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Mhc Class Ii Molecules

Invariant chain (Ii) contributes in a number of distinct ways to the proper functioning of major histocompatibility complex (MHC) class II molecules. These include promoting effective association and folding of newly synthesized MHC class II alpha and beta subunits, increasing transit of assembled heterodimers out of the endoplasmic reticulum (ER), inhibiting class II peptide binding, and facilitating class II movement to or accumulation in endosomes/lysosomes. Although the cytoplasmic tail of Ii makes a key contribution to the endocytic localization of class II, the relationship between the structure of Ii and its other diverse functions remains unknown. We show here that two thirds of the lumenal segment of Ii can be eliminated without affecting its contributions to the secretory pathway events of class II folding, ER to Golgi transport, or inhibition of peptide binding. These same experiments reveal that a short (25 residue) contiguous internal segment of Ii (the CLIP region), frequently found associated with purified MHC class II molecules, is critical for all three functions. Together with other recent findings, these results raise the possibility that the contributions of Ii to the early postsynthetic behavior of class II may depend on its interaction with the class II binding site. This would be consistent with the intracellular behavior of unoccupied MHC class I and class II molecules as incompletely folded proteins and imply a related structural basis for the similar contributions of Ii to class II and of short peptides to class I assembly and transport.

scholarly journals Antigen processing by epidermal Langerhans cells correlates with the level of biosynthesis of major histocompatibility complex class II molecules and expression of invariant chain.

1990 ◽  
Vol 172 (5) ◽  
pp. 1459-1469 ◽  
Author(s):  
E Puré ◽  
K Inaba ◽  
M T Crowley ◽  
L Tardelli ◽  
M D Witmer-Pack ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Langerhans Cells ◽  
Antigen Processing ◽  
Class Ii ◽  
Invariant Chain ◽  
Protein Antigens ◽  
Histocompatibility Complex ◽  
Mhc Class Ii Molecules ◽  
Epidermal Langerhans Cells

Two prior studies with a small number of T cell lines have shown that the presentation of native protein antigens by epidermal Langerhans cells (LC) is regulated. When freshly isolated, LC are efficient antigen-presenting cells (APC), but after a period of culture LC are inefficient or even inactive. The deficit in culture seems to be a selective loss in antigen processing, since cultured LC are otherwise rich in major histocompatibility complex (MHC) class II products and are active APC for alloantigens and mitogens, which do not require processing. We have extended the analysis by studying presentation to bulk populations of primed lymph node and a T-T hybrid. Only freshly isolated LC can be pulsed with the protein antigens myoglobin and conalbumin, but once pulsed, antigen is retained in an immunogenic form for at least 2 d. The acquisition of antigen, presumably as MHC-peptide complexes, is inhibited if the fresh LC are exposed to foreign protein in the presence of chloroquine or cycloheximide. The latter, in contrast, improves the efficacy of antigen pulsing in anti-Ig-stimulated B blasts. In additional studies of mechanism, we noted that both fresh and cultured LC endocytose similar amounts of an antigen, rhodamineovalbumin, into perinuclear granules. However, freshly isolated LC synthesize high levels class II MHC molecules and express higher amounts of the class II-associated invariant chain. Fresh LC are at least 5-10 times more active than many other cells types in the level of biosynthesis of MHC class II products. These findings provide a physiologic model in which newly synthesized MHC class II molecules appear to be the principal vehicle for effective antigen processing by APC of the dendritic cell lineage. Another APC, the B lymphoblast, does not appear to require newly synthesized MHC class II molecules for presentation.

scholarly journals Dynamics of Major Histocompatibility Complex Class II Compartments during B Cell Receptor–mediated Cell Activation

2002 ◽  
Vol 195 (4) ◽  
pp. 461-472 ◽  
Author(s):  
Danielle Lankar ◽  
Hélène Vincent-Schneider ◽  
Volker Briken ◽  
Takeaki Yokozeki ◽  
Graça Raposo ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Mhc Class Ii ◽  
Cell Receptor ◽  
Class Ii ◽  
B Cell Receptor ◽  
Cathepsin S ◽  
Invariant Chain ◽  
Histocompatibility Complex ◽  
Mhc Class Ii Molecules

Antigen recognition by clonotypic B cell receptor (BcR) is the first step of B lymphocytes differentiation into plasmocytes. This B cell function is dependent on efficient major histocompatibility complex (MHC) class II–restricted presentation of BcR-bound antigens. In this work, we analyzed the subcellular mechanisms underlying antigen presentation after BcR engagement on B cells. In quiescent B cells, we found that MHC class II molecules mostly accumulated at the cell surface and in an intracellular pool of tubulovesicular structures, whereas H2-M molecules were mostly detected in distinct lysosomal compartments devoid of MHC class II. BcR stimulation induced the transient intracellular accumulation of MHC class II molecules in newly formed multivesicular bodies (MVBs), to which H2-M was recruited. The reversible downregulation of cathepsin S activity led to the transient accumulation of invariant chain–MHC class II complexes in MVBs. A few hours after BcR engagement, cathepsin S activity increased, the p10 invariant chain disappeared, and MHC class II–peptide complexes arrived at the plasma membrane. Thus, BcR engagement induced the transient formation of antigen-processing compartments, enabling antigen-specific B cells to become effective antigen-presenting cells.

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.

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