A VH‐Associated Idiotype in Human Anti‐Tetanus Antibodies

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Abstract
An anti‐idiotypic (α Id) serum was induced against anti‐tetanus toxoid (α TET)‐reactivc F(ab')2 fragments of a single donor. After appropriate adsorption the serum was shown to react only with α TET F(ab')2 fragments and not with F(ab')2 fragments deplcted of α TET reactivity or anti‐diphtheria toxoid (DIP) or anti‐purified protein derivative (α PPD) F(ab')2 fragments of this donor. Inhibition studies with soluble TET indicated that the anti‐idiotypic serum partly reacts with determinants close to or within the antigcnic binding site. When tested on a small panel of α TET F(ab')2 fragments derived from unrelated donors, one out of four donors tested showed cross‐reactivity. When tested on α TET F(ab')2 fragments derived from related family members, the donor's father and two sisters were found to cross‐react, whereas the mother and two other sisters did not. The observed cross‐reactivity was independent of the litres of α TET antibodies in the serum. Furthermore, two‐dimensional gel electrophoretic studies carried oui on α TET IgG of Id‐positive or Id‐negative family members indicated that the expression of idiotypic determinants is linked to a particular heavy chain. Immunofluorescent staining with α Id and cytofluoro‐graphic analysis of donor T‐lymphoblast proliferation in response to TET showed that the T cells did not express Id determinants found on his α TET antibodies.