Effect of temperature on the reactivities of polyreactive and monospecific monoclonal IgG antibodies

In this study, the reactivities of two groups of murine monoclonal antibodies (mAbs) of the IgG isotype were compared by ELISA at various temperatures (Ts) (range: 4-56 degrees C). The first group was constituted of 4 polyreactive mAbs that reacted with various antigens (Ags), such as actin, myosin and tubulin. The second contained 3 commercially available monoreactive mAbs specific to actin, myosin or tubulin. The binding of the monospecific mAbs to their Ags was modified only slightly at the other Ts compared with binding at 37 degrees C. In contrast, the activities of the polyreactive IgGs were considerably modified depending upon the T during incubation on Ag. In a second series of experiments, the effects of the T of the washes and conjugate incubation on the mAb/Ag interaction were evaluated. In these experiments, all steps and incubations were carried out at 37 or 4 degrees C. The values were then compared to those obtained when the washes and conjugate incubation were performed at room temperature. These two protocols generated very little difference in terms of monospecific mAbs. For polyreactive IgG, the values were generally lower when the incubations were carried out at 4 degrees C. However, on the whole, the effect of the T of the washes and conjugate incubation was negligible when the mAb/Ag complex had already formed on the polystyrene plate. Furthermore, at 4 degrees C, 2 of the polyreactive mAbs behaved like monospecific antibodies, while the other 2 remained polyspecific. It can be concluded from these experiments that the reactivities of polyreactive mAbs are more T-sensitive than those of monoreactive mAbs. This seems to indicate that they may possess a more plastic structure and thus may more easily undergo deformation when subjected to non-physiological conditions. In addition, the fact that the polyreactive mAbs showed the same variations for the 3 Ag tested suggests that the same paratope could be involved in all reactions.