Requirement for protein synthesis in antigen processing by B cells.
The role de novo protein synthesis plays in Ag processing by B cells was investigated. Cycloheximide (CHX) inhibited Ag processing in normal and transformed B cells. B lymphoblastoid cells required a 2-6 hr longer CHX pretreatment period than splenic B cells to inhibit Ag processing function. Immunoprecipitation experiments demonstrated that the half-life of class II/invariant chain (Ii) complexes was similar in normal and transformed B cells. B lymphoblastoid cells differed from splenic B cells in that a significant fraction of total class II-associated p31 Ii was modified with sialic acid (Ip). The kinetics of loss of class II-associated Ip in CHX-treated cells correlated with loss of Ag processing function. In addition, the half-life of a subpopulation of class II molecules that are unstable in sodium dodecyl sulfate at room temperature was greater in transformed cells. Our results suggest that B lymphoblastoid cells, but not splenic B cells, contain a long-lived pool of class II/Ii complexes that can bind and present peptides generated in endosomal compartments for a significant time period after cessation of protein synthesis.
Department of Pathology, Emory University School of Medicine, Atlanta, Georgia 30322.
K M
KM
Soreng
J C
JC
Moore
M A
MA
Sherman
P E
PE
Jensen
D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects / Q000502:physiology*; D000944:Antigens, Differentiation, B-Lymphocyte; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000502:physiology; D006825:Hybridomas; D051379:Mice; D008807:Mice, Inbred BALB C; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D011500:Protein Synthesis Inhibitors; C045084:invariant chain; D003513:Cycloheximide