GSBS Student Publications

Title

Class II MHC molecules and antigen enter the same vesicles during internalization by resting B lymphocytes

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology

Date

9-1-1990

Document Type

Article

Medical Subject Headings

Animals; Antibody Specificity; Antigens; B-Lymphocytes; Endocytosis; Histocompatibility Antigens Class II; Immunohistochemistry; Kinetics; Mice; Mice, Inbred DBA; Spleen; Subcellular Fractions

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Efficient presentation of Ag by a B cell to a T cell requires that Ag bind to the Ag receptor (Ig) on the B cell, after which it is internalized into an acid compartment where it is modified and returned to the cell surface in the context of class II MHC molecules. It remains uncertain whether processed Ag binds to class II which has been internalized and recycled with Ag, or to nascent class II inside the cell. To determine if cell surface class II enters the same vesicles as Ag, or is excluded during internalization of Ag which is bound to the B cell receptor, 5- and 16-nm gold particles were labeled with anti-class II and anti-Ig, respectively. Cells were incubated at 37 degrees C and internalization of these particles was observed using electron microscopy. By 10 min, 60-75% of the B cell sections contained vesicles with gold particles inside them. Between 40 and 64% of these vesicles had both 5- and 16-nm particles. Maximum internalization occurred by 30-60 min, and by 2 hr the number of small and large particles on the B cell surface became constant or increased, respectively. Both kinds of particles moved from electron-lucent to electron-dense vesicles as the incubation time increased, although a portion of the anti-class II particles remained in electron-lucent vesicles. These data clearly show that labeled, cell surface class II is not selectively excluded from Ag-containing vesicles during Ag internalization. Thus, cointernalization of Ag and class II may represent a mechanism by which processed Ag meets class II.

Rights and Permissions

Citation: Cell Immunol. 1990 Sep;129(2):404-13.

Related Resources

Link to article in PubMed

Journal Title

Cellular immunology

PubMed ID

2383898