The dual function of the splenic marginal zone: essential for initiation of anti-TI-2 responses but also vital in the general first-line defense against blood-borne antigens

A Zandvoort, W Timens*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

182 Citations (Scopus)

Abstract

The splenic marginal zone (S-MZ) is especially well equipped for rapid humoral responses and is unique in its ability to initiate an immune response to encapsulated bacteria (T-cell independent type 2 (TI-2) antigens). Because of the rapid spreading through the blood, infections with blood-borne bacteria form a major health risk. To cope with blood-borne antigens, a system is needed that can respond rapidly to a great diversity of organisms. Because of a number of unique features, S-MZ B cells can respond rapid and efficient to all sorts of blood-borne antigens. These unique features include a low blood flow microenvironment, low threshold for activation, high expression of complement receptor 2 (CR2, CD21) and multireactivity.

Because of the unique high expression of CD21 in a low flow compartment, S-MZ B cells can bind and respond to TI-2 antigens even with relatively low-avid B cell receptors. Although TI-2 antigens are in general poorly opsonized by classic opsonins, a particular characteristic of these antigens is their ability to bind very rapidly to complement fragment C3d without the necessity of previous immunoglobulin binding. TI-2 primed S-MZ B cells, already by first passage through the germinal centre, will meet antigen-C3d complexes bound to follicular dendritic cells, allowing unique immediate isotype switching. This explains that the primary humoral response to TI-2 antigens is unique in its characterization by a rapid increase in IgM concurrent with IgG antibody levels.

Original languageEnglish
Pages (from-to)4-11
Number of pages8
JournalClinical and Experimental Immunology
Volume130
Issue number1
Publication statusPublished - Oct-2002

Keywords

  • splenic marginal zone
  • B cells
  • memory
  • T-cell independent type 2 antigens
  • pneumococcal polysaccharides
  • MEMORY B-CELLS
  • INDEPENDENT TYPE-2 ANTIGENS
  • HUMORAL IMMUNE-RESPONSE
  • VARIABLE REGION GENES
  • HUMAN LYMPHOCYTES-B
  • PNEUMOCOCCAL POLYSACCHARIDES
  • ACQUIRED-IMMUNITY
  • SIGNAL-TRANSDUCTION
  • ANTIBODY-RESPONSES
  • TI-2 ANTIGENS

Cite this