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Mouse monoclonal antibodies induced by anti-allotype antibody display internal images of the rabbit VHa1 allotype: Direct visualization by immunoelectron microscopy

1986; Wiley; Volume: 16; Issue: 6 Linguagem: Inglês

10.1002/eji.1830160619

1521-4141

Victor H. Van Cleave, Kuruganti G. Murti, Dennis W. Metzger,

RNA and protein synthesis mechanisms

Abstract We have previously shown that injection of adult rabbits with anti‐immunoglobulin (Ig) antibody (Ab) induces the expression of genetically unexpected Ig markers, i.e. , a1 allotypic determinants. We now show that these rabbit Ig markers can also be induced in mice by a similar treatment; in the latter case the a1 determinants are located in the antigen‐combining site and thus represent “internal images”. Two monoclonal antibodies (mAb) were developed from mice treated with anti‐allotype Ab. These mAb (a) were reactive with all homologous and heterologous anti‐a1 Ab but not normal Ig; (b) efficiently inhibited the binding of rabbit a1 Ig to anti‐a1 Ab; and (c) elicited the production of anti‐allotype Ab when injected into normal mice. To determine whether the al‐like determinants on these mAb were located in the antigen‐combining site, immunoelectron microscopy was utilized to directly visualize Ab complexes. Complexes composed of intact Ab and anti‐a1 Fab fragments yielded uniform binding patterns which were identical to those produced by anti‐idiotypic reactions. In each case, an identical tip‐to‐tip binding configuration was observed with a single Fab fragment attached at an approximate 180° angle to the V region terminus of each Ab arm. In contrast, rabbit a1 Ig bound as many as two anti‐a1 fragments per Ig arm; these fragments were attached laterally and at right angles to the intact molecule. These mAb thus provide the first direct evidence that Ab2β determinants are located in, or near, the antigen‐combining site.