EXPLORING THE MECHANISMS OF ANTIGEN-PROCESSING BY CELL FRACTIONATION

It is becoming increasingly clear that most of the intracellular compa rtments that contain MHC class II products in antigen-presenting cells simply represent the conventional endosomes and lysosomes that are ex pressed in all cell types. Data from recent cell fractionation studies , however, predominantly those using electrophoresis techniques, show that a population of class-II-containing vesicles exists that may comp rise a class of endosomes that are specialized for antigen processing. Strong support for this possibility comes from the observation that s uch specialized structures, designated class II vesicles (CIIV), are p articularly abundant in mature dendritic cells. (C) Current Biology Lt d ISSN 0952-7915.