Complement Opsonization Is Required for Presentation of Immune Complexes by Resting Peripheral Blood B Cells This information is current as Susan A. Boackle, Margaret A. Morris, V. Michael Holers of September 25, 2021. and David R. Karp J Immunol 1998; 161:6537-6543; ; http://www.jimmunol.org/content/161/12/6537 Downloaded from References This article cites 42 articles, 29 of which you can access for free at: http://www.jimmunol.org/content/161/12/6537.full#ref-list-1 Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 25, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 1998 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. Complement Opsonization Is Required for Presentation of Immune Complexes by Resting Peripheral Blood B Cells1 Susan A. Boackle,* Margaret A. Morris,† V. Michael Holers,* and David R. Karp2† Complement receptor 2 (CD21, CR2) is a B cell receptor for complement degradation products bound to Ag or immune complexes. The role of CD21 in mediating Ag presentation of soluble immune complexes by resting B cells was studied. Complement-coated immune complexes were formed by the incubation of influenza virus with serum from immune donors. These complexes bound to peripheral blood B cells in a complement-dependent manner. The binding required CD21 or, to a lesser extent, complement receptor 1 (CR1, CD35). B cells pulsed with immune complexes containing complement elicited a response from a panel of influenza-specific T cell clones, while those pulsed with immune complexes formed in the absence of complement did not. The expression of the early activation marker CD69 and the costimulatory molecule CD86 were not induced by CD21 ligation alone, suggesting that CD21-mediated Ag presentation occurs independently of B cell activation. Up-regulation of these markers required Downloaded from exposure to T cell factors elicited by the recognition of Ag derived from complement-containing immune complexes. These findings suggest that binding of Ag to CD21 enables Ag-nonspecific B cells to participate in the activation of Ag-specific T cells in a process that occurs independently of well-characterized B cell activation events. The Journal of Immunology, 1998, 161: 6537–6543. he development of a mature immune response requires complexes in the course of complement activation. Studies per- the collaboration between B and T lymphocytes. Ag is formed in vivo have confirmed the critical role of CD21 in the http://www.jimmunol.org/ T internalized by B cells and processed into peptides that generation of a normal humoral immune response. Normal murine are presented to T cells in the context of specific MHC class II Ab responses to T-dependent Ags are inhibited by pretreatment molecules. Ag-specific T cells recognize these complexes via with mAbs to CD21 or soluble CD21 (4–6). Mice rendered CD21- TCR/CD3 with signals through these receptors resulting in the deficient using gene-targeting techniques demonstrate similar al- up-regulation of CD40 ligand on the T cell surface. Cross-linking terations (7, 8). B cell CD21 was found to be critical for these of B cell CD40 by CD40 ligand induces the expression of the effects based on studies in bone marrow chimeras, in which the costimulatory molecules CD80 and CD86 (1, 2), which bind CD28 immune defects were corrected by reconstitution with bone mar- on T cells. The T cells then secrete IL-2, which enhances B cell row from CR21/1 MHC-matched littermates. The role of B cell maturation and proliferation. An individual B cell is able to initiate CD21 was further confirmed in mice created by RAG-2-deficient by guest on September 25, 2021 these responses only if it presents adequate numbers of class II- blastocyst complementation (9). These animals specifically lack peptide complexes to specific T cells. Although nonspecific fluid- CD21 on their B cells, but have normal expression on their fol- phase endocytosis of Ag occurs poorly in resting B cells, Ag can licular dendritic cells (FDC). These studies demonstrated that the be internalized efficiently by binding to specific Ag receptors (3). targeting of complement-coated immune complexes to FDC is not Nonetheless, B cells are not believed to be critical for Ag presen- sufficient for the development of a normal humoral response in the tation because of the low frequency of Ag-specific B cells for any absence of complement receptors on B lymphocytes. Additional particular Ag. studies have supported an adjuvant-like role of complement in B Ag can be targeted to other B cell surface receptors, including cell responses. C3d linked to hen egg lysozyme (HEL)3 by recom- complement receptors such as CD21. CD21 is a 140-kDa glyco- binant DNA techniques was 1,000–10,000 times more immuno- protein located on the surface of mature B lymphocytes, as well as genic than HEL alone, inducing enhanced Ca21 mobilization in on follicular dendritic cells, pharyngeal epithelial cells, thymo- vitro as well as augmenting primary and secondary Ab responses cytes, and some T cells. It binds the terminal products of C3 deg- in vivo (10). radation that have become covalently bound to Ag or immune CD21 may participate in the development of a normal immune response by several mechanisms. First, ligation of CD21 may re- sult in various signals that are critical for normal B cell responses. *Departments of Medicine and Immunology, Division of Rheumatology, University Previous studies have shown that B cell proliferation and differ- of Colorado Health Sciences Center, Denver, CO 80262; and †Simmons Arthritis Research Center, University of Texas Southwestern Medical Center, Dallas, TX entiation can be induced by cross-linking CD21 with polymeric 75235 C3d or certain anti-CD21 mAbs in the presence of T cell factors Received for publication June 23, 1998. Accepted for publication August 20, 1998. (11, 12) or phorbol esters (13). CD21 also plays a synergistic role The costs of publication of this article were defrayed in part by the payment of page in the activation of B cells induced by ligation of surface IgM, as charges. This article must therefore be hereby marked advertisement in accordance measured by calcium mobilization (14), proliferation (15), or in- with 18 U.S.C. Section 1734 solely to indicate this fact. duction of c-fos mRNA levels (16). Many of the signaling effects 1 This work was supported by National Institute of Health Grant U01-AI34621 induced by CD21 have been attributed to its physical association (D.R.K.), National Institute of Health Training Grant T32-AR07055 (S.A.B.), and National Institute of Health Grant R01-AI31105 (V.M.H.). Portions of this work have with CD19 and CD81 (TAPA-1) on the surface of B lymphocytes been previously been presented in abstract form at the Annual Meeting of the Amer- ican College of Rheumatology, Orlando, FL, October 1996. 2 Address correspondence and reprint requests to Dr. David R. Karp, University of 3 Abbreviations used in this paper: HEL, hen egg lysozyme; KLH, keyhole limpet Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235- hemocyanin; PE, phycoerythrin; CR, complement receptor; TAPA-1, target of anti- 8884. E-mail address: [email protected] proliferative antibodies-1. Copyright © 1998 by The American Association of Immunologists 0022-1767/98/$02.00 6538 B CELL ANTIGEN PRESENTATION REQUIRES COMPLEMENT OPSONIZATION (17–19). Signaling through CD19 has been reported to augment ological Reagent and Reference Repository (anti-H3; Braton Biotech, that of soluble IgM, with coligation of the two receptors lowering Rockville, MD). The murine mAbs to CD21 (HB5), CD3 (OKT3), CD14 the threshold for B cell activation by two orders of magnitude (20). (63D3), CD16 (B73.1), and CD11b (LM2/1.6.11) were obtained from the American Type Culture Collection (Manassas, VA). Phycoerythrin (PE)- Alternatively, CD21 may participate in the generation of a nor- labeled anti-CD19 (B43) was obtained from PharMingen (San Diego, CA). mal immune response by internalizing and directing C3-bound Ag Biotinylated anti-CD19 (B4) was obtained from Coulter (Miami, FL). into the class II processing pathway of B cells. This was first sug- FITC-labeled anti-CD69 was obtained from Becton Dickinson (Sunnyvale, gested by Lanzavecchia et al. (21) who demonstrated an aug- CA). FITC-labeled CD86 was obtained from The Binding Site (Birming- ham, U.K.). Rabbit polyclonal Ab to CD21, Ab73, was generated by im- mented anti-Ig-specific T cell response to transformed B cells munization with a soluble human CD21 produced by recombinant bacu- pulsed with anti-CD21 mAbs. Other investigators have utilized lovirus in insect cell culture. It recognizes short consensus repeats 1–2 of C3-linked ligands for CD21 to demonstrate this same phenome- CD21 including the C3d binding site (V.M.H., unpublished data). The non. In one report, tetanus toxoid was covalently cross-linked to mouse mAb to CD32, AT10 (26), was the kind gift of Dr. P. M. Morganelli C3b and C4b (22). In a second, immune complexes were generated (Veterans Administration Hospital, White River Junction, VT). The mouse mAb to CD35, 3D9, was the kind gift of Dr.