Reaction of germinal centers in the T-cell-independent response to the bacterial polysaccharide alpha(1-->6)dextran.
Primary immunization of BALB/c mice with alpha(1-->6)dextran (DEX), a native bacterial polysaccharide, induces an unexpected pattern of splenic B-cell responses. After a peak of antibody-secreting B-cell response at day 4, deposition of dextran-anti-dextran immune complexes, as revealed by staining with both dextran and antibodies to dextran, occurs and persists in splenic follicles until at least the fourth week after immunization. Antigen-specific B cells appear and proliferate in such follicles, leading by day 11 to development of DEX-specific germinal centers as characterized by the presence of distinct regions of DEX+ peanut agglutinin-positive (PNA+) cells. At this time, fluorescence-activated cell sorter analysis also reveals the appearance of a distinct population of DEX+ PNA+ splenic B cells. In contrast, DEX+ PNA- cells, characterized by intense cytoplasmic staining, are present outside of splenic follicles, peak at day 4 to day 5, and persist until at least day 28. The frequency of these cells correlates with DEX-specific antibody-secreting cells, as detected by the ELISA-spot assay. Thus, in addition to the expected plasma cellular response, the typical T-cell-independent type II antigen, DEX, surprisingly also elicits the formation of antigen-specific germinal centers. These observations raise fundamental questions about the roles of germinal centers in T-cell-independent immune responses.
Wang
D
D
Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
Wells
S M
SM
Stall
A M
AM
Kabat
E A
EA
D000818:Animals; D000936:Antigen-Antibody Complex; D003911:Dextrans / Q000276:immunology*; D005434:Flow Cytometry; D007070:Immunoglobulin A / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D037102:Lectins; D007934:Leuconostoc / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D019887:Peanut Agglutinin; D010950:Plasma Cells / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013154:Spleen / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D000936:Antigen-Antibody Complex; D003911:Dextrans; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D037102:Lectins; D019887:Peanut Agglutinin; D011135:Polysaccharides, Bacterial; C041999:alpha-1,6-dextran