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Murine monoclonal antibodies (MoAb) were prepared by immunizing mice with human monoclonal rheumatoid factors from patient with mixed cryoglobulinaemia. Indirect solid phase radioimmunoassay and haemagglutination inhibition were used to screen the MoAb, Reacuity patterns of MoAb were determined using (a) polyclonal and monoclonal lgM proteins. (b) monoclonal IgM proteins Iron patients with neuropathy (c) monoclonal and Polyclonal IgM antigammaglobulins and (d) various isolated VkIII -positive immunoglobulins. Several patterns were obtained: MoAb reacting with private idiotype's determinants. with VkIlIb-related determinants. and with cross reactive idiotypes (CRI). Two .MoAb of the second type reacted with VkllIb-positive immunoglobulins and light chains regardless of their antigenic activity. Another MoAb reacted with VKIII light chains only when in association with μ heavy chains. MoAb at the third type detained distinct CR1 systems. One of these was restricted to antigammaglobulins and another also involved neuropathy associated monoclonal IgM proteins. All MoAb clearly reacted with a minor population or normal polyclonal IgM. except for the MoAb detecting private idiotype determinants. Studies using inhibition of binding by enzyme-linked immunosorbents assay showed that polyclonal IgM antigammaglobulins `nay carry a CRI determinant detected by one ot the MoAb. This CRI system. defined by the MoAb Gb 86.3, was similar to but not identical with the previously described CRI which is widely prevalent among IgM antigammagiobulins of rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

The function of Fc receptors (FcR) on mouse spleen cells as detected by a sensitive rosetting system using antibody-labeled bovine erythrocytes as indicator cells was shown to be inhibited by anti-Ia antiserum. Furthermore, the la specificities of each I-region sublocus (I-1A, I-1B, I-C) seem to be associated with FcR, since FcR function was also inhibited when the blocking anti-Ia antiserum recognized only restricted la specificities. Antiserum directed against antigens coded for by the K-end of the major histocompatibility complex did not inhibit FcR function. The function of C3 receptors and Fc receptors on macrophages and Fc-receptor-positive cells in the fetal liver was not inhibited by anti-Ia antiserum. These findings are discussed in view of a possible arrangement of Fc receptors and Ia antigens on the cell membrane. [ABSTRACT FROM AUTHOR]

This study demonstrated that Fc rosettes detected by antibody-labeled bovine erythrocytes can be inhibited by immune complexes of rabbit IgG (b4 allotype) and anti-b4 IgG, thus showing that these complexes effectively compete for the receptor for erythrocyte-antibody rosettes. Incubation of mouse lymphocytes with goat F(ab')2 anti-mouse IgG did not inhibit Fc rosettes. When immunoglobulin on murine and human B lymphocytes was redistributed in a polar cap on the membrane by interaction with anti-immunoglobulin antibodies, the number of Fc rosettes after 'capping' was unchanged; most of the indicator erythrocytes, however, were distributed in a cap as well. This erythrocyte cap was superimposed on the immunoglobulin cap. [ABSTRACT FROM AUTHOR]

The major rheumatoid factor cross reactive idiotype (RCRI), defined by prototypic monoclonal rheumatoid factors (RFs), is expressed as a dominant idiotype by pokeweed mitogen induced plasma cells obtained from seropositive (RF+) patients with rheumatoid arthritis (RA). Some patients who meet clinical diagnostic criteria for RA set by the American Rheumatism Association fail to express RFs at any time during their clinical course. To determine if seronegative (RF-) patients with RA, so designated by the latex fixation, Rose-Waaler classic binding assays, or a RF enzyme linked immunosorbent assay (ELISA), express the RCRI in the absence of detectable RFs we examined pokeweed mitogen plasma cells from these patients by indirect immunofluorescence. In addition, we used an inhibition ELISA to detect RCRI bearing molecules in the sera of RF- patients with RA. Five of 10 RF- patients with RA had a high prevalence of RCRI+ plasma cells (16-49% of total pokeweed mitogen plasma cells in culture). Six of 20 RF- patients with RA had high serum concentrations of molecules marked by the RCRI, equivalent to 21-110 micrograms/ml of RCRI+ reference monoclonal IgM RF. Four of five patients who expressed the RCRI in high prevalence in pokeweed mitogen plasma cells, also demonstrated high concentrations of RCRI in their sera detected by inhibition ELISA. There was significant concordance of RCRI expression determined by the two different assays. Four RF- patients with RA who expressed RCRI in their whole sera had hidden RFs detected in their 19S and, in one case, 7S serum fraction. Detection of RF related molecules in whole sera by the expression of RCRI in RF- patients with RA identifies a subgroup of RF- patients with RA who possess hidden RFs. Some RF- patients with RA can express the major RCRI in pokeweed mitogen plasma cells and in their sera and therefore are related to patients with prototypic Waldenstrom's macroglobulinaemia, who produce RCRI+ 19S IgM monoclonal RFs. [ABSTRACT FROM AUTHOR]

The IgD-immunoglobulin producing plasma cells oft human spleens have been localized with specific antisera and the type of the light chains present in each of them has been determined by sequential staining with anti-K and anti-L antisera. About 87 per cent of IgD cells have L-type light chains. This is in accord with the prevalence of L-type light chains in IgD myeloma proteins. [ABSTRACT FROM AUTHOR]

Purified IgA molecules, prepared from rabbit colostrum, have the same allotypic markers of the heavy (H) polypeptide chain as are present in the serum IgG of the same individual. When the dimeric molecule of rabbit colostral IgA is dissociated into its sub-units by reduction, its capacity to absorb an appropriate anti-allotypic antibody is quantitatively identical with that of the serum IgG of the same animal. It is concluded that there are neither qualitative nor quantitative differences in the antigenic expression of the allotypic determinants of the a locus present on the rabbit γ and α chains. [ABSTRACT FROM AUTHOR]

The cells that produce group 1 and group 2 γ-globulins have been localized in human lymphoid tissues. This has been done with the use of antisera specific for group 1 or group 2 γ-globulins prepared by immunizing rabbits with purified Bence-Jones proteins of the corresponding group and subsequently conjugated with different fluorochromes. The immunofluorescence observations have shown that in the red pulp of the spleen of adult humans two populations of plasma cells, present in approximately equal numbers, can be differentiated on the basis of the type of γ-globulin produced. The cells in the germinal centres of lymphoid follicles in the spleen and lymph nodes appear, instead, to contain both group 1 and group 2 γ-globulins. [ABSTRACT FROM AUTHOR]