Demonstration of C3 receptors on frozen sections of normal lymphoid tissue and malignant lymphomas using various EAC complexes.

Abstract

The occurrence and distribution of complement receptors (C3R) were investigated on frozen sections from normal lymphoid tissue and from 185 cases of malignant lymphoma. Various EAC complexes were used: vital EA or glutaraldehyde-fixed EA coated with mouse complement (EAC mouse and Glu-EAC mouse, respectively), human complement (EAC human and Glu-EAC human), or complement from C6-deficient rabbits (EACra-C6-def, Glu-EACra-C6-def). The different EAC complexes showed varying affinity for C3R: Glu-EAC human > EAC mouse = EACra-C6-def > Glu-EAC mouse = Glu-EACra-C6-def > EAC human. The EAC complexes differed not only in their receptor affinity but also in their pattern of binding. On frozen sections of tonsils, EAC mouse, EAC human and EACra-C6-def adhered exclusively to germinal centers and the follicular mantle, whereas Glu-EAC mouse, Glu-EAC human and Glu-EACra-C6-def adhered not only to germinal centers and the follicular mantle but also to parafollicular areas and sometimes to interfollicular regions. The various EAC complexes were also assayed for reactivity to C3b receptors of human erythrocytes and C3R of human tonsil cells. Human erythrocytes (C3b receptor+ and C3d receptor− did not react with EAC mouse, EAC human or EACra-C6-def whereas tonsil cells (C3b and C3d receptor+) showed positive reactions with these complexes. In contrast, Glu-EAC mouse, Glu-EAC human and Glu-EACra-C6-def displayed marked affinity for both the C3b receptors of human erythrocytes and the C3Rof tonsil cells. In connection with previously reported data, these findings indicate that (a) EAC mouse, EAC human and EACra-C6-def react only with receptors for C3d, whereas Glu-EAC human, Glu-EAC mouse and Glu-EACra-C6-def are bound by C3b receptors and probably by C3d receptors as well, and (b) germinal center cells and follicular mantle lymphocytes express C3b and C3d receptors whereas cells in parafollicular areas and those in the interfollicular zone bear only C3b receptors.