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Updated: Aug 8, 2026
Generation of Human CD40-activated B cells
Published on: October 17, 2009
Surface immunoglobulin ligands and cytokines differentially affect proliferation and antibody production by human
Y Nawata1, A M Stall, L A Herzenberg
1Department of Immunology, Syntex Research, Palo Alto, CA 94304.
Insights
This study differentiates human B lymphocyte subsets (CD5+ and CD5-) and examines their proliferation and antibody production. Findings suggest CD5+ B cells require two signals for activation and primarily produce IgM, potentially playing a role in natural immunity.
Area of Science:
- Immunology
- Cell Biology
Background:
- B lymphocytes are crucial for adaptive immunity.
- Distinct B cell subsets, like CD5+ B cells, may have specialized functions.
- Understanding B cell activation requirements is key to immune response modulation.
Purpose of the Study:
- To investigate the differential proliferation and antibody production of human CD19+ CD5+ and CD19+ CD5- B cell subsets.
- To elucidate the signaling requirements for CD5+ B cell activation and cytokine-dependent responses.
- To explore the potential role of CD5+ B cells in natural immunity.
Main Methods:
- Isolation of human peripheral blood B lymphocyte subsets (CD5+ and CD5-) using FACS sorting.
- Activation of B cells with Staphylococcus aureus Cowan I (SAC) and anti-mu beads.
- Culture of B cells with recombinant human interleukins (IL-1 alpha, IL-2, IL-4, IL-6) and assessment of proliferation and Ig production.
- Analysis of surface activation marker expression (Leu-23, Leu-21, IL-2R, CD23).
Main Results:
- Both CD5+ and CD5- B cells proliferate upon SAC stimulation, with IL-2 augmenting CD5- B cell proliferation.
- CD5- B cells respond to anti-mu beads, while CD5+ B cells require a second signal (e.g., IL-4) for proliferation.
- CD5- B cells produce IgM, IgG, and IgA, whereas CD5+ B cells predominantly produce IgM.
- Cytokines IL-1 and IL-6, particularly with IL-2, enhance antibody production.
Conclusions:
- CD5+ B cells exhibit distinct activation requirements, needing two signals for proliferation, unlike CD5- B cells.
- The restricted IgM production by CD5+ B cells suggests a specialized role, possibly in natural immunity.
- Differential cytokine responsiveness and Ig isotype production highlight functional heterogeneity between human B cell subsets.
Abstract:
Normal human peripheral blood B lymphocytes were separated into CD19+ CD5+ and CD19+ CD5- subsets by dual-color FACS sorting. In most experiments the cells were activated with Staphylococcus aureus Cowan I (SAC) and cultured in the absence or presence of recombinant human IL-1 alpha, IL-2, or IL-6, or combinations of these cytokines. Unstimulated CD5+ and CD5- B cells showed a comparable, low level of incorporation of [3H]thymidine into DNA. SAC stimulated proliferation of CD5+ and CD5- B cells, and this proliferation was augmented by IL-2 in the case of CD5- B cells. Anti-mu beads stimulated some proliferation of the CD5- subset and augmented SAC-induced proliferation of these cells. In contrast, anti-mu beads did not stimulate proliferation of the CD5+ subset and had no effect on SAC-induced proliferation of these cells. CD5+ B cells activated by anti-mu beads were stimulated to proliferate in the presence of IL-4, but not in the presence of IL-2. These observations support the interpretation that two signals are required for proliferation of CD5+ B cells. Using a two-step culture system, SAC activation itself did not induce Ig production by either subset of purified B cells. However, it primed the cells for antibody production in the presence of IL-2. IL-1 and IL-6 by themselves augmented antibody formation by these cells slightly, if at all. However, IL-6, and to a lesser extent IL-1, augmented antibody production in the presence of IL-2. Under the culture conditions used CD5- B cells produced IgM, IgG, and IgA whereas the CD5+ B cells produced almost exclusively IgM. The expression on B cells of surface activation markers was analyzed after culture for 2 days with SAC or anti-mu beads. In both subsets expression of Leu-23 and Leu-21 was increased, with some differences in intensity (Leu-23 greater in CD5+ cells, Leu-21 greater in CD5- cells). SAC increased IL-2R expression to a greater extent than anti-mu beads. In neither subset was expression of CD23 increased. These observations are discussed in the context of the possible role of the CD5+ subset of B lymphocytes as components of a system of natural immunity.
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