A Member of the Dendritic Cell Family That Enters B Cell Follicles and Stimulates Primary Antibody Responses Identified by a Mannose Receptor Fusion Protein

Abstract

Dendritic cells (DCs) are known to activate naive T cells to become effective helper cells. In addition, recent evidence suggests that DCs may influence naive B cells during the initial priming of antibody responses. In this study, using three-color confocal microscopy and three-dimensional immunohistograms, we have observed that in the first few days after a primary immunization, cells with dendritic morphology progressively localize within primary B cell follicles. These cells were identified by their ability to bind a fusion protein consisting of the terminal cysteine-rich portion of the mouse mannose receptor and the Fc portion of human immunoglobulin (Ig)G1 (CR-Fc). In situ, these CR-Fc binding cells express major histocompatibility complex class II, sialoadhesin, and CD11c and are negative for other markers identifying the myeloid DC lineage, such as (CD11b), macrophages (F4/80), follicular DCs (FDC-M2), B cells (B220), and T cells (CD4). Using CR-Fc binding capacity and flow cytometry, the cells were purified from the draining lymph nodes of mice 24 h after immunization. When injected into naive mice, these cells were able to prime T cells as well as induce production of antigen-specific IgM and IgG1. Furthermore, they produced significantly more of the lymphocyte chemoattractant, macrophage inflammatory protein (MIP)-1α, than isolated interdigitating cells. Taken together, these results provide evidence that a subset of DCs enters primary follicles, armed with the capacity to attract and provide antigenic stimulation for T and B lymphocytes.

Recombinant human lactoferrin expressed in glycoengineered Pichia pastoris: effect of terminal N-acetylneuraminic acid on in vitro secondary humoral immune response

“…This would suggest that reconstruction of MTX-inhibited secondary humoral immune response requires interaction of LF with cells expressing neuraminic dependent receptors. The prime candidate for such a receptor is sialoadhesin, a sialic acid-binding receptor, found on murine tissue macrophages [10,14,28] and dendritic cells [4], and perhaps the CD22 marker on B cells that bears sequence similarity to sialoadhesin [20]. Nevertheless, the use of specific anti-sialoadhesin antibody, with no apparent crossreactivity with CD22, makes such a possibility very unlikely.…”

“…To this mixture, dithiothreitol (DTT) was added to a final concentration of 10 mM and incubated at 37°C for 1 h. Iodoacetic acid in Tris base neutralized with NH 4 OH was added to a final concentration of 40 mM and incubated in the dark for 1 h. The sample was then bufferexchanged and concentrated with a Vivaspin 50,000 MWCO concentrator to roughly 1 mg/ml in 100 mM Tris-HCl, pH 7.4. The sample was subsequently split into four aliquots with each receiving 2.6 μg of trypsin in 10 mM HCl.…”

Extracellular lysosome‐associated membrane protein‐1 (LAMP‐1) mediates autoimmune disease progression in the NOD model of type 1 diabetes

“…BALB/c mice were subcutaneously immunized with OVA in alum, and 24 h later the draining LN were obtained for DC isolation as described elsewhere [35]. LN tissues were digested with 2.5 mg/ml of collagenase IV (Worthington, Freehold, NJ) and 1%/ml deoxyribonuclease (Sigma, St Louis, MO).…”

“…When tissue appeared to be completed digested, the enzyme reaction was stopped by the addition of ice-cold IMDM. After three washes using cold IMDM, digested tissue was submitted to discontinuous Percoll density gradient centrifugation and T cells were obtained by harvesting the 1.087-1.083 and 1.083-1.079 density interfaces [35]. Cell numbers and viability were assessed by trypan blue dye exclusion.…”

Low-affinity B cells transport viral particles from the lung to the spleen to initiate antibody responses

“…MZ B cells in turn have been reported to transport blood-borne Ags into the Bcell FO in a C-dependent manner (22)(23)(24)(25). Alternatively, Ag can be transported into splenic and lymph node FO by a subset of macrophages/DCs identified by their ability to bind a fusion protein of the cysteine-rich domain of mannose receptor fused to the Fc portion of human IgG (CRFc + ) (26)(27)(28). We have recently shown that blood-borne VLPs are efficiently trapped in the MZ from where they are transported to FDCs in B-cell FO in a process dependent upon complement receptor expression on B cells as well as natural Ab (29).…”