Ligand-induced redistribution and augmentation of surface-bound myeloma protein on MOPC 315 plasmacytoma cells

Immunization with the light chain and the VL domain of the isologous myeloma protein 315 inhibits growth of mouse plasmacytoma MOPC315

Prior immunization of BALB/c mice with free light chains from myeloma protein 315 (L315) and its variable domain (VL315) inhibited the growth of subcutaneously injected MOPC315 tumour cells. The growth suppression observed after immunization with L315 was equivalent to that which resulted from immunization with the complete M315. VL315 and non-polymerized L315 did not elicit specific antibodies. Polymerized L315 induced both suppression of MOPC315 growth and antibodies specific for free L315; however, these antibodies did not react with the complete M315, nor were they absorbed by MOPC315 tumour cells. The data indicate that the suppression of tumour growth was mediated by specifically sensitized cells acting in the absence of antibodies against M315 or L315. Immunization with the variable domain of the heavy chain from M315 (VH315) had no effect on the growth of MOPC315. The M315 fragments and subunits that induced growth suppression were thus identical with those capable of inducing T helper cells in BALB/c mice.

Suppression of in vitro monoclonal human rheumatoid factor synthesis by antiidiotypic antibody. Target cells and molecular requirements

Previous studies have indicated that antiidiotypic antibody can modulate expression of idiotype both in vivo and in vitro. Although the precise mechanisms underlying modulation of idiotype expression by antiidiotype remains unclear, a requirement for intact IgG antiidiotypic antibody has been suggested and T cells appear to play a role in some systems. We have studied peripheral blood mononuclear leukocytes (MNL) from a patient with a B cell lymphoma and a circulating IgMK rheumatoid factor (RF) paraprotein in an effort to delineate mechanisms involved in regulation of idiotype expression by antiidiotypic antibody. 1-10% of MNL from this patient could be cytoplasmically stained with specific F(ab')2 antiidiotypic antibody. MNL from the patient spontaneously synthesized IgM RF in culture that possessed the same idiotype as the circulating IgM RF paraprotein. Production of RF by MNL was suppressed by pretreatment with either intact IgG or the F(ab')2 fragments of antiidiotypic antibody (50% inhibitory concentration was 0.2 and 1.1 micrograms/culture, respectively). In contrast, the Fab' fragment of antiidiotypic antibody was not inhibitory (up to 57 micrograms/culture) despite retaining demonstrable antiidiotype activity. Suppression of RF production was not observed over the same concentration range with the IgG or F(ab')2 fractions of a non-cross-reactive antiidiotypic antibody prepared against another monoclonal IgMK RF paraprotein or with IgG or F(ab')2 fractions prepared from normal rabbit serum. Inhibition of RF production by antiidiotypic antibody did not require T cells. Antiidiotypic antibody decreased intracellular and extracellular levels of idiotype indicating diminished synthesis of idiotype by the patient's B cells. Synthesis of IgM RF by MNL obtained from unrelated donors was not suppressed by the antiidiotypic antibody specific for the patient's paraprotein. The results indicate that (a) antiidiotypic antibody is capable of directly suppressing human B cell release of idiotype, (b) the bivalent antigen-binding fragment (F[ab']2) of antiidiotypic antibody is sufficient for mediating such suppression, (c) an intact Fc portion of antiidiotypic antibody enhances suppression of idiotype, and (d) antiidiotypic antibody inhibits idiotype expression by suppressing synthesis of idiotype.

H--2-linked genes control immune response to V-domains of myeloma protein 315

Immunoglobulins function as antigen receptors of B lymphocytes and as effector molecules for elimination of foreign antigens. Recently, other functions have been revealed: for example, idiotypes (antigenic sites of variable (V) domains) bound on the surface of plasmacytomas can act as tumour-specific transplantation antigens. Moreover, optimal maturation of B lymphocytes of a given idiotype into antibody-secreting cells seems to require assistance from two different kinds of helper T cells (Th), one bearing receptors complementary or similar to that idiotype, and another that recognizes the antigen. To learn more about recognition of V regions by Th, we have used V-domains of the immunoglobulin A (IgA) (lambda 2) myeloma protein M315 produced by the BALB/c plasmacytoma MOPC315 (ref. 7) as carriers for anti-hapten responses. We report here that the Th response to the V-domain of the heavy chain (VH) and the light chain (VL) of M315 seems to be under H--2-linked immune response (IR) gene control.

The cellular reaction in normal and tumour-bearing mice following intraperitoneal glucan injection

The effect of a single intraperitoneal injection of yeast glucain in C3D2 mice was studied. The optimal dose for the induction of a cellular exudate was 0.4 mg/kg, producing 17.6 x 10(6) cells on day 7 after injection. The number of T-cells, B-cells and macrophages in this exudate was analysed by the use of morphology, immunofluorescence and the non-specific esterase staining. An increase in both T-cells, B-cells and macrophages was found after glucain injection. There was an 8-fold increase in macrophages, but the increase lasted only 14 days. The increase in T-cells was smaller, but lasted at least 35 days. The effect of pretreatment with glucan on the development of an inoculated syngeneic methyl cholanthrene induced sarcoma was studied. No effect on tumour take could be demonstrated, but differences in T-cell, B-cell and macrophage content of the developing tumour were found. A strinking feature was a prolonged increase in tumour T-cell content.

IgG-binding sites on macrophage cell membrane. II. Mobility of Fc receptors induced by the interaction with their corresponding IgG ligands

Mouse peritoneal macrophages were charged with IgG molecules in monomeric (mIgG), heat-aggregated (agIgG) or antigen-complexed (acIgG) form. Upon exposure to 37 degrees C, all bound IgG ligand types are redistributed on the cell surface due to the mobilization of their corresponding Fc receptor (FcR). The major findings regarding the fate of FcR on macrophages bearing IgG ligands are as follows: (a) the FcR involved in the binding of cytophilic molecules has a slow movement on the cell membrane and forms patches but never caps, while the opsonic type of FcR is rapidly capped; (b) the mobility of IgG-binding sites was temperature-dependent and was affected differently by sodium azide; this metabolic inhibitor enhances the disappearance of mIgG from the cell surface but decreases the capping and the disappearance of polymeric ligands; (c) both FcR types are probably ingested when complexed with specific ligand, and consequently, the rebinding of homologous IgG molecules is reduced, the clearing induced by agIgG or acIgG binding being much more extensive; and (d) cells cleared of their opsonic types of FcR are able to regenerate the receptor molecules with 8 h of incubation at 37 degrees C.

The plasma cell differentiation antigen PC.1 is absent in CH3/Tif and present in C3H/HeJ

(C3H/TifxDBA/2)F1 mice, immunized with viable BALB/c plasmacytoma MOPC315 cells, produce antibodies directed against a cell-surface antigen. The strain and tissue distribution of this antigen was identical to that of the plasma cell differentiation alloantigen PC.1. The antigen is absent in the mouse strain C3H/Tif but is present in the closely related substrain C3H/HeJ. This is the third difference between surface structures of the B-cell lineage of C3H/Tif and C3H/HeJ mice.