Human B cell activation. Evidence for diverse signals provided by various monoclonal anti-IgM antibodies (original) (raw)
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Journal of Experimental Medicine, 1988
The perturbation of membrane immunoglobulin (mIg)' on B lymphocytes can have diverse effects on B cell physiology. Immature B cells and certain activated B cell populations are particularly susceptible to inhibition (tolerance) after mIg crosslinking (1-4), while mature, resting B cells are characteristically stimulated to DNA synthesis (4-6) . Because both stimulatory and inhibitory signal transduction appear to involve similar early biochemical reactions (1, 6), it is of some interest that the ligand dose requirements for achieving these distinct functional phenomena have generally been found to differ by one or more orders of magnitude (3, 7-10) . This suggests that the ligand binding requisites for triggering B cell tolerance may be significantly different from those for directly triggering B cell clonal expansion .
Molecular Immunology, 1987
The domain binding specificity of 19 murine anti-human IgM monoclonal antibodies (MoAbs) that have shown considerable heterogeneity in the transduction of stimulatory and inhibitory signals to B lymphocytes was evaluated by competition radioimmunoassays. Through the use of: (i) enzymatic fragments of IgM which each encompass more than a single C, domain, i.e. Fc,~ and F(ab'),p, (ii) isolated single domains, Cpc,, Cp,, and Cpq, and (iii) mu heavy chain disease proteins, nine anti-IgM MoAbs were found to have Cp, domain specificity, five to have Cpc, specificity, and five others to have Q4 specificity. Ineffective binding to isolated p chain demonstrated that Cp,-specific MoAbs were directed to epitopes which require light chain for expression. The lack of binding of the Cp,-specific MoAbs to CNBr cleavage fragments of Fc,~ suggest that the determinants recognized by these MoAbs may also be conformational in nature. Cross-inhibition analyses were used to determine the number of unique epitopes recognized by the anti-IgM MoAbs. Results from these experiments showed that: (i) eight of the nine MoAbs specific for Cp, likely bind to a single epitope, or very proximate epitopes, (ii) the five Q-specific MoAbs recognize at least three distinct epitopes, and (iii) the five Cp,-specific MoAbs each recognize a separate determinant. A comparison of the known B cell activating properties of these MoAbs with their specificitv for the various segments of the IgM molecule indicate that mitogenicity cannot be attributed to selective binding to any one domain.
The Journal of experimental medicine, 1983
The present study demonstrates the minimal, optimal, and synergistic signals involved in the activation of normal human peripheral blood and tonsillar B cells to proliferation. Initial activation signals were delivered to B cells by low concentrations of anti-mu antibody which did not induce proliferation by themselves. However, marked synergy was seen when anti-mu antibody was added to cultures in the presence of monoclonal B cell growth factor (BCGF) obtained from a human T-T cell hybrid such that the B cells underwent substantial proliferation. This latter proliferation was seen without maturation into Ig-secreting cells, which indicates that the BCGF is not a differentiation signal but a signal that drives the cell up to but not beyond the proliferative phase. Of note was the fact that B cells reflected differential sensitivity on the basis of size to either the activation signal delivered by anti-mu antibody or the proliferative signal delivered by BCGF. BCGF directly stimulate...
Journal of Experimental Medicine, 1984
A monoclonal antibody, AB1, was established with activated human B cells as immunogen. AB1 stained activated B cells but not activated T cells. Its selective reactivity to activated B cells was further documented by its nonreactivity to activated T cells, resting T and B cells, monocytes, granulocytes, bone marrow cells, leukemic cells, and cells from cell lines of T, B, and myeloid lineages. Upon activation, the antigen appeared on B cells as early as 3-4 h after stimulation and was fully expressed by 38 h. The expression of this antigen was not dependent on the presence of B cell stimulatory factor(s). Anti-IgM antibodies by themselves induced its expression. AB1 inhibited B cell proliferation that was induced by a low dose anti-IgM antibody and conditioned medium containing B cell stimulatory factor. It did not inhibit B cell proliferation induced by either high doses of anti-IgM antibodies or by formalinized Staphylococcus aureus. It also failed to inhibit T cell mitogenesis. Th...
Characterization of Two Murine Monoclonal Antibodies Reactive with Human B Cells
Scandinavian Journal of Immunology, 1985
We describe two monoclonal antibodies, HH1 and HH2. Both reacted selectively with surface immunoglobulin (sIg)-positive human B cells. Both antibodies stained on average 7-8% of peripheral blood mononuclear cells. They have not been found to react with cells or cell lines of other haematopoietic cell lineages, except that HH2 was positive on a small percentage of cells of the erythroid cell line K562. The molecular weight of the HH1 antigen was 95 kD, as established by Western blotting. Neither of these two antibodies reacted with Ig determinants, Fc receptors, complement receptors, or known class-I or class-II molecules. A combination of these antibodies was used in a direct panning technique for high-yield enrichment of normal B lymphocytes from peripheral blood. The enriched B cells could be further purified by lysis of T cells (final yield, on average 72 +/- 8% of initial B cells) or by a second panning (yield, 35 +/- 11%). The purified B cells contained less than 1% contaminating T cells and less than 0.5% monocytes and were used in an assay for B-cell-stimulating factor which they showed a normal and very reproducible proliferative response.
Receptors for IgM on Human B Lymphocytes
Scandinavian Journal of Immunology, 1978
Using a rosette technique with IgM coated bovine red blood cells (EA-IgM) receptors for IgM can be demonstrated on human B-lymphocytes. While in the peripheral blood B cells with IgM receptors are found only occasionally, between 7 and 33%. mean 16%, of tonsil B-lymphocytes exhibit receptors for IgM. This was shown in double marker studies using EA-IgM for the demonstration of IgM receptors and fiuorochrome labelled conjugates for the demonstration of S-IgD. S-IgM and B cell antigens. These receptors are specific for IgM. they can be completely blocked by IgM-anti OVA complexes and partially by free IgM. but not at all by aggregated human IgG. They are sensitive to trypsin and pronase but reconstitute after further incubation at 37°C. These data show that not only T and CLL cells but also some normal B-lymphocytes have receptors for IgM. We favour the view that CLL lymphocytes may derive from these B-lymphocytes. which may represent a certain maturation step in B cell development.
Blood, 1987
A functional study of several human malignant B cell populations has indicated that occasional leukemic clones are extraordinarily sensitive to signal transduction through membrane IgM. One isolated hairy cell leukemia (HCL) with low background DNA synthesis was stimulated to significant levels of DNA synthesis when cultured with high (100 micrograms/mL) concentrations of soluble anti-IgM ligands. In contrast to the activation of normal peripheral blood polyclonal B cells, this DNA synthesis was completely independent of accessory T cell factors. Although the HCL clone could also be induced to enter S phase by incubation in media supplemented with only activated T cell supernatant, culture of the clone with activated T cell supernatant plus anti-IgM Ab resulted in DNA synthesis that was significantly less than that induced by either activator alone. Factor(s) in T cell supernatant appear to modulate the leukemic clone so that the binding of ligand to membrane IgM is perceived as an ...
Receptors for IgM on Certain Human B Lymphocytes
The Journal of Immunology
A receptor for IgM was demonstrated on the surface of human B lymphocytes by using a rosette technique with ox erythrocytes coated with rabbit IgM antibody (EAM). Lymphocytes forming rosettes with EAM did not bind sheep red cells, had membrane Ia-like antigens and, in some instances, surface immunoglobulin. The specificity of EAM rosettes was confirmed by inhibition experiments with purified human Ig. IgM but not IgG molecules inhibited the rosette reaction. In addition, inhibition of EAM rosettes with IgM fragments showed that the receptor has affinity for a part of the molecule located in the Fc portion. By analogy with the receptors previously found on certain human T cells, receptors for IgM were not detected on freshly isolated B cells, but were expressed after overnight culture in IgM-free media. Studies on different human lymphoid tissues showed that IgM receptors are expressed on a limited percentage of both circulating and noncirculating B cells. In addition to normal B cel...
The Journal of Immunology
The transgenic (TG) mouse strain 207-4, carries mu a + kappa transgenes ligated to the anti-phosphocholine (PC) VH1 and V kappa 24 V region genes from the MOPC-167 myeloma. Although B cells from mice carrying these transgenes respond both in vivo and in vitro to thymus-dependent Ags, they failed to proliferate in response to soluble goat anti-mu Ab or other soluble anti-Ig reagents. On the other hand, B cells from the Sp6 mu kappa anti-trinitrophenyl TG mouse line proliferated normally after stimulation with soluble anti-mu. However, the 207-4 anti-PC transgene positive (TG+) splenic B cells proliferated when stimulated with anti-mu, anti-idiotype, anti-allotype, or PC-conjugated to Sepharose beads. TG+ B cells were also induced to proliferate when stimulated with anti-Lyb-2; thus, their defect may be restricted to signaling through sigM. The lack of response to soluble anti-mu could not be reversed by addition of IL-4, by removal of T cells, by addition of anti-FcR Ab, or by stimul...
Proceedings of the National Academy of Sciences, 1984
Previous studies have shown that treatment with antibodies to the murine I-A antigen encoded in the major histocompatibility complex attenuates experimental allergic encephalitis and experimental autoimmune myasthenia gravis. These studies were conducted with SJL mice, an inbred strain that is highly susceptible to the induction of these diseases. Here we show that injection of monoclonal anti-I-A antibody in the amounts used for the above studies rapidly depletes B cells. Fluorescence-activated cell sorter (FACS) multiparameter analysis of the B-cell subpopulations in treated animals shows that maximum depletion occurs around 5 days after treatment and that recovery of some subpopulations is still incomplete 1 month later. SJL mice are more sensitive to this Bcell depletion and recover more slowly than putatively normal C3H.Ighb (CKB) mice. Some components of the primary, secondary and tertiary IgG antibody responses are reduced in anti-I-A-treated SJL animals immunized after the first and second anti-I-A injections. The persistence of some antibody response impairment well beyond the time when anti-I-A disappears raises a note of caution concerning human therapy protocols based on the injection of anti-Ia antibodies.