The identity of light chains of monoclonal IgG and monoclonal IgM in one patient

A highly conserved determinant on human rheumatoid factor idiotypes defined by a mouse monoclonal antibody

Different human IgM rheumatoid factor (IgM RF) idiotypes have been described defined by polyclonal rabbit anti-idiotypic antibodies. These antisera do not allow clear genetic analysis of the idiotypic determinants, be they cross-reactive or private. Therefore, we tried to obtain a set of monoclonal anti-idiotypic antibodies directed against RF idiotypes. Purified IgM RF serum from a patient with classical rheumatoid arthritis was used to immunize BALB/c mice. The spleen cells were fused with Sp 2/0 Ag 14, a nonsecreting mouse myeloma cell line, and a hybrid producing monoclonal anti-idiotypic antibody was selected. The mouse antibody, an IgG1 kappa, reacts with an identical or similar determinant located on (or close to) the binding site of all tested monoclonal or polyclonal IgM RF from totally unrelated patients with Waldenströms's macroglobulinemias or rheumatoid arthritis. The monoclonal antibody also reacts with 2 rheumatoid arthritis patients' IgG RF and with a low proportion of normal polyclonal IgM without detectable RF activity. An hypothesis is proposed to explain the existence of a such highly conserved determinant on RF idiotypes.

The clinical aspects of biclonal gammopathies. Review of 57 cases

Between 1966 and 1979, biclonal gammopathy was recognized in 57 patients. Clinical and laboratory features differentiated three groups: biclonal gammopathy of undetermined significance, 37 cases (65 percent); multiple myeloma, nine cases (16 percent); and lymphoproliferative disease--including lymphoma, macroglobulinemia, chronic lymphocytic leukemia and unclassified lymphoproliferative disorders--11 cases (19 percent). With biclonal gammopathy of undetermined significance, symptomatic multiple myeloma developed after two years in one patient; the others remained stable. One patient with multiple myeloma had osteosclerotic myeloma and a severe sensorimotor peripheral neuropathy, and another presented with plasma cell leukemia. In the remainder response to therapy and survival were much the same as in patients with multiple myeloma with a monoclonal protein. Patients with lymphoproliferative disease responded to chemotherapy like that for monoclonal gammopathy. Of the 57 patients, 30 (53 percent) had IgG and IgA components, 15 (26 percent) had IgG and IgM, six had two IgG components, three had IgA and IgM, one had IgA proteins, one had IgA and IgE and 1 had triclonal gammopathy. Of the 115 light chains, 70 percent were kappa; the chains were both kappa and lambda in 63 percent of biclonal pairs. In many cases, serum electrophoresis produced only a single band on the acetate strip, and the biclonal gammopathy was not recognized until immunoelectrophoresis was done. Although the clinical features of biclonal gammopathy and its response to therapy are similar to those of monoclonal gammopathy, this subject is of importance because of the lack of clinical data in the literature.

Nonsecretory multiple myeloma. Immunohistologic and ultrastructural observations on two patients

Two well documented examples of nonsecretory multiple myeloma were studied by electron microscopic and immunohistologic methods. In one case, repeat studies revealed no intracytoplasmic immunoglobulins, and the cells displayed a "plasmacytoid" appearance with poor development of rough endoplasmic reticulum and Golgi regions. In the other case, most cells contained intracytoplasmic immmunoglobulins of a monoclonal type and the ultrastructural appearance was that of cells actively engaged in protein synthesis. These findings and others in the literature suggest that myelomas without an M component can be separated into nonproducers and true nonsecretors of immunoglobulins. In one case, immunofluorescence of bone marrow smears with double labels demonstrated three different plasma cell populations: those producing either monoclonal immunoglobulins M (IgM) or A (IgA) and those synthesizing simultaneously IgM and IgM. Dual immunoglobulin production, although known to occur in myelomas with paraproteinemia, has not been previously documented in the nonsecretory variety.

Studies on IgA and IgA monoclonal proteins derived from a single patient. Evidence for identical light chains and variable regions of the heavy chain

Two immunoglobulins, IgA(K) and IgG(K), were isolated from the serum of a single patient with two monoclonal components (biclonal proteins). After chain separation, the light chains from each molecule were found to be identical by the following criteria: electrophoretic mobilities under various pH and dissociating conditions, amino acid compositon, fingerprint analysis of tryptic peptides and of 14C-succinylated chymotryptic peptides, and amino acid sequence of the N-terminal 40 residues. The heavy chains were indistinguishable for the N-terminal 45 amino acid residues. These data are consistent with the hypothesis that a single heavy chain variable (VH) region may be associated with two different heavy chain constant (CH) genes.

Partial characterization of the shift from IgG to IgA synthesis in the clonal differentiation of human leukemic bone marrow-derived lymphocytes

An unusual B-cell proliferation was noted in an individual (Tun) which was characterized by the presence of two separate populations of chronic lymphocytic leukemia (CLL) cell staining on the surface and in the cytoplasm for either IgG(k) or IgA(k). Utilizing an idiotypic antiserum prepared from the associated serum monoclonal IgG(k) protein the idiotype was detected on the surface and in the cytoplasm of both the IgG- and IgA-bearing cell populations. These observations are consistent with a common clonal origin and a switch mechanism involving IgG and IgA synthesis. Sequential-labeling of Surface Ig and intracellular Ig with antisera conjugated to opposite fluorochromes documented the progressive maturation of the terminal differentiation of the IgA-bearing cell population at a level before morphologically distinct plasma cells. The distribution and pattern of surface and cytoplasmic IgG and IgA staining in individual cells suggest that the direction of switching is from IgG to IgA synthesis. The demonstration of shared idiotypic specificity between the IgG- and IgA-bearing populations is consistent with a transition in Ig heavy chain synthesis resulting from an alternation in the CH gene. It is concluded that certain CLL clones may manifest a switch from IgG to IgA synthesis at a level of B-cell differentiation which encompasses both the B lymphocyte and the Ig-synthesizing plasma cell.

Organization of immunoglobulin genes: reiteration frequency of the mouse kappa chain constant region gene

Hybridization kinetic analyses with synthetic DNA indicate that there are only two to three copies of the kappa constant region gene per haploid genome. This result lends weight to the argument that the immunoglobulin light chain is encoded by more than one continuous gene sequence.

Monoclonal production of both IgM and IgG1 antihapten antibody

The anti-DNP antibodies produced by primary and secondary splenic foci were analyzed for heavy chain class by a radioimmunoassay, using iodinated, purified goat antimouse micro-chain antibody and goat antimouse gamma1 chain antibody. The frequency of primary and secondary foci producing both IgM and IgG1 anti-DNP antibody (16% and 14%, respectively) was considerably higher than that which would be predicted by a random distribution. It would thus appear that IgM and IgG1 antibody can be made by the clonal progeny of a single precursor cell.

Immunofluorescent evidence for cellular control of synthesis of variable regions of light and heavy chains of immunoglobulins G and M by the same gene

Two distinct paraproteins (IgG(2)-K and IgM-K) from one patient shared identical light chains and significant portions of the variable regions of the heavy chains. Idiotypic determinants on the IgG and IgM molecules were shared. Earlier studies, using class-specific antisera, showed that these paraproteins were produced by two different populations of cells. The present study, using rhodamine and fluorescein conjugates of the anti-idiotype antisera, demonstrates that all plasma cells that contain immunoglobulin, whether IgG or IgM, stained with anti-idiotype antisera; this occurred irrespective of whether the antisera were made originally against the patient's IgG or IgM. This, plus previous data, indicates that both populations of cells share genetic information for the constant and variable regions of light chains and significant portions of the heavy-chain genes. These, and other cited data, strongly suggest the occurrence of a switch-over from IgM to IgG synthesis in the same cell during the course of the normal immune response.

Suppression of immunoglobulin G synthesis as a result of antibody-mediated suppression of immunoglobulin M synthesis in chickens

Development of heterogeneity of immunoglobulin classes has been investigated in the chicken by studying the effects of antibody-mediated suppression of IgM synthesis. Treatment of 13-day embryos with purified goat antibodies to IgM resulted in the elimination of IgM-containing cells from the bursa of Fabricius of 16- and 19-day embryos. When combined with bursectomy at hatching, administration of anti-IgM in ovo suppressed the synthesis not only of IgM but also of IgG. A number of experimental birds lacked detectable circulating immunoglobulins, plasma cells, and germinal centers when killed at 10 weeks of age. Contrasting results were obtained when IgM synthesis was suppressed after bursectomy at hatching. Birds so treated produced little or no IgM but synthesized normal amounts of IgG. The results suggest that, within the bursal environment, IgG-producing cells arise exclusively from cells that previously synthesized IgM. A model for generation of antibody variability is presented.

A variable region subclass of heavy chains common to immunoglobulins G, A, and M and characterized by an unblocked amino-terminal residue

Heavy chains of IgG, IgA, and IgM classes of human immunoglobulins were compared by N-terminal residue determination and partial amino acid sequence analysis. A third subclass of the variable region of heavy chains was observed; an unblocked glutamic acid as the N-terminal residue is characteristic of this subclass. Our results indicated that the heavy chain variable region subclasses are not class specific, and that a given heavy chain variable region may be found in association with constant regions for mu-chains, alpha-chains, or gamma-chains of various subclasses.

Evidence for control of synthesis of the varible regions of the heavy chains of immunoglobulins G and M by the same gene

Previous work indicated that the light chains of a monotypic immunoglobulins G2-K and M-K from a single patient (Ti1) are identical. Our present data show that the monotypic immunoglobulins G and M share idiotypic determinants not present in their isolated light chains or in any of a large number of other immunoglobulins tested, and that amino acid sequences of the first 27 residues from the NH(2)-terminal end of the gamma- and mu-chains are identical. These results support the hypothesis that at least two genes control the synthesis of each heavy and light chain and suggest that the monotypic immunoglobulin G and monotypic immunoglobulin M of this patient share three of the four genes involved. It is proposed that, during normal immunoglobulin synthesis, different cells of a single clone synthesize immunoglobulins M and G, and that the light chains and the variable segments of the heavy chains of the proteins of the two classes are identical within the clone. A genetic switching mechanism is suggested.