Anti-idiotypic regulation of IgA expression in myeloma cells

T cells in myeloma

The current trend to develop immunotherapy strategies for patients with myeloma and other B cell malignancies has stimulated considerable interest in the functional state of the T cell population in these patients. Expanded clones of T cells exist in many patients with myeloma and their presence is associated with an improved survival. However, isolating T cells with tumour specificity has proven to be a difficult task and clinical immunization trials have so far failed to achieve a significant response. There is now evidence that tumour specific T cells are either tolerized or deleted following antigen presentation and that idiotype-derived, immunodominant tumour peptides may not exist in all patients. In order to develop more effective immunotherapy strategies for patients with myeloma, further studies are urgently required to identify the most appropriate tumour antigen, the nature of the interactions which take place during antigen presentation, and how to promote the cytotoxicity of autologous T cells.

Generation of T cell clones binding F(ab')2 fragments of the idiotypic immunoglobulin in patients with monoclonal gammopathy

Lymphocytes from two patients with multiple myeloma stage I and one patient with monoclonal gammopathy of undetermined significance were found to proliferate specifically in response to low concentrations of F(ab')2 fragments of the autologous M component. T cell clones isolated from repeatedly stimulated cultures bound specifically the autologous idiotype and proliferated after addition of soluble idiotype and exogenous interleukin-2. The majority of clones were CD8+ and showed negligible staining for CD4. Idiotype-binding clones could not be isolated from cultures of lymphocytes from a healthy control stimulated under the same conditions. The study provides support for the existence of idiotype-reactive T cells in monoclonal gammopathies. Such cells might have a regulatory role on the tumor cell clone and may be important for a future therapeutic approach.

Prospects for the treatment of B cell tumors using idiotypic vaccination

Manipulation of the immune system in order specifically to attack autologous tumor cell has been a distant goal, largely due to the poor definition of tumor-associated antigens. By focussing on B cell lymphomas which express a molecularly defined clonal marker, the idiotypic immunoglobulin, it has been possible to generate autologous anti-idiotypic responses which suppress individual tumors. Studies of the components of these responses are providing insight into host effector mechanisms which can be activated against tumors, and also into the many strategies adopted by the target cells in order to avoid such attack. Promising results in various animal models where tumor bearers can be treated by idiotypic immunization have led to the point where application of this approach to the treatment of certain categories of human B cell lymphoma can be considered.

A sensitive method for testing the effect of immunoglobulin binding factor on Ig secretion by hybridoma B cells

A microtiter plate assay to detect the effect of immunoglobulin binding factor (IBF) on Ig secretion by hybridoma B cells is described. This technique permits the analysis of Ig secretion by only 200-400 hybridoma B cells using a PFC assay and an ELISA, and therefore increases the IBF/cell number ratio. This increase allows the detection of a strong IBF-mediated inhibitory effect on Ig secretion by hybridoma B cells, which is otherwise difficult to obtain reproducibly. The technique is simple, does not require any transferring step and is convenient, since it permits large numbers of samples to be tested. It can be extended to test IBF for all isotypes or other lymphokines that affect Ig secretion.

Immunoglobulin-specific suppressor T cells

This article has considered evidence that supports the occurrence and functional importance of suppressor T cells that are directed to B cell targets. Cells with these features have been demonstrated in experimental animals and in humans. The designation "suppressor" comes from the serologic phenotype of these cells as well as from their functional property of noncytotoxic inhibition of B cell function. Distinct suppressor T cells with these properties have been identified that effect antigen-, idiotype-, isotype-, and allotype-specific suppression of B cell function. While such cells had been suspected from earlier studies of normal immune responses, the development of monoclonal B cell models using tumor cells has provided a means to readily detect these suppressor T cells and to investigate the mechanisms by which they mediate their effects. Tumor models have proved to be powerful tools in the effort to identify and analyze the elements that underlie the complexity of immune responses. Combined with the insights provided by molecular genetic approaches and flow cytometry, functional and responsive lymphoid tumor cells are being used with increasing frequency to address basic immunoregulatory issues. An important family of suppressor T cells with B cell targets are those that express surface Fc receptors, elaborate immunoglobulin-binding factors, and appear to participate in the regulation of immunoglobulin heavy chain class expression. In addition to their importance in the regulation of heavy chain class expression during normal immune responses, alterations in FcR+ T cells in a number of disease states may provide clues that will lead to a better understanding of disorders of immune regulation.

Influence of a minor recurrent idiotype on the regulation of immune response: route dependence

Sp6, a BALB/c hybridoma, produces anti-TNP IgM antibodies (AB), which carry a minor recurrent idiotype (ID). Despite the fact that only about 20% of BALB/c anti-TNP AB carry the Sp6 ID, injection of Sp6-coated spleen cells (Sp6-SC) significantly influenced the anti-TNP B cell response. Repeated intratrail (i.t.) or intravenous (i.v.) injections of Sp6-SC resulted only in a minor increase of the anti-TNP background response. When mice consecutively were challenged with TNP-horse red blood cells (HRBC), i.t. injections of Sp6-SC resulted in a 2-3-fold increase in the number of anti-TNP plaque-forming cells (PFC), while i.v. injection of Sp6-SC displayed no effect on a primary anti-TNP response. But, after i.v. as well as i.t. application of Sp6-SC, it was not possible to obtain hapten-specific suppression by i.v. injection of TNP-haptenized lymphocytes. In vitro characterization of the underlying mechanism revealed that the helper effect, which only was observed after i.t. injection, was due to a Lyt-1+ population, not adhering to Sp6-coated plates, while counterregulation of hapten-specific suppression was found in a Lyt-2+ population, adhering to Sp6-coated plates. Hence, depending on the route of priming, injection of AB with a recurrent ID can augment the response towards the nominal antigen either directly via activation of helper cells or indirectly via activation of counterregulatory cells.

Components of immune function studied with lymphoid tumors

Lymphoid tumors have proven to be productive models for investigating genetic, biochemical, physiological and developmental mechanisms of lymphoid cells. Lymphoid tumors of a given lineage exhibit a spectrum of phenotypes from clones whose features overlap extensively with their normal counterparts to clones whose features are not obviously represented in normal lymphoid populations. In addition to the phenotypic continuum represented in a library of related tumors, many clones exhibit phenotypic diversity spontaneously or in response to various stimuli. As laboratory technology has advanced many interesting biological features of lymphoid tumors have become amenable to precise analysis. Progress made in understanding the mechanisms that underly the phenotypic diversity and plasticity of lymphoid tumor cells has the dual impact of improving our knowledge of malignant and normal lymphoid cells.

Depletion of murine anti-azobenzenearsonate plaque-forming cells by derivatized polyacrylamide beads

The depletion of secondary p-azobenzenearsonate plaque-forming cells (ABA-PFC) by affinity columns substituted with ABA was dependent on the primary dose, times elapsed after priming, and the nature of the side-arm on the columns. Thus, higher priming doses of ABA coupled to keyhole limpet haemocyanin (50-500 micrograms of ABA-KLH in complete Freund's adjuvant (CFA] favoured depletion of ABA-PFC by ABA coupled to a 6- aminocaproyltyrosine side-arm (SAC-TYR-ABA beads), whereas ABA-PFC from mice primed with 1 microgram of ABA-KLH in CFA were never depleted; this latter population were only depleted by ABA coupled to a histamine side-arm (HIST-ABA beads) 7 months after priming. These data are consistent with the notion that two specificities, HIST-ABA and TYR-ABA, appear to emerge independently, lower priming doses inducing the preferential appearance of the HIST-ABA specificity.