Non-specific binding of mouse immunoglobulins by swollen-bodied astrocytes--a potential source of confusion in human brain immunohistochemistry.

All classes of non-immune mouse immunoglobulins bind non-specifically to the cytoplasm of modified astroglial cells, swollen-bodied astrocytes, when applied to paraffin or frozen sections of human brain tumors and various reactive states. The binding could be inhibited by preincubation with normal human serum, and a proportion of the cells, which reacted with mouse immunoglobulins, showed spontaneous presence of various classes of human immunoglobulins. The Fc part of the immunoglobulins was involved in the binding, since preincubation of mouse immunoglobulins with protein A effectively inhibited the binding and the F(ab)2 fragments of mouse immunoglobulins showed no affinity to modified astroglial cells. The non-specific binding reported here effectively precludes the use of whole mouse immunoglobulins in the immunohistochemistry of human brain pathology.