Periapical granulomas have been investigated histologically, immunohistologically using polyclonal and
monoclonal antibodies, as well as electronmicroscopically. Lesions were formed by inflammatory granulation tissue frequently with foci of purulent exudation and
fibrosis. Most numerous were plasma cells usually in cellular regions of the granulation tissue where they were tightly pressed. Of other cellular types were numerous lymphocytes, fibroblasts, less frequent were macrophages, scattered granulocytes and mast cells. More than a half of the plasma cells were
IgG positive, about 20%
IgA positive, up to 10%
IgM, rarely
IgE and sporadically
IgD positive cells. In the vascular walls and their surrounding as well as in the phagocytes fine granular to granular positivities of C3 and C4 components of the
complement were present. The majority of lymphocytes beared markers of T lymphocytes of which the T-suppressor markedly prevailed over the T-helper lymphocytes. In electron microscopy the plasma cells were most frequent. They were usually close to each other, sometimes with a disintegrated cytoplasmic membrane and non-damaged organelles being free around the nucleus. Mast cells were numerous and did not show any signs of marked degranulation. Rich production of
immunoglobulins as well as the presence of
IgG and
IgM positive material in phagocytes, and the presence of positivities of the C3 and C4 components of the
complement in the surrounding of the vessels and in phagocytes on the other hand supported the presumption that
immune complexes participate in the pathogenesis of
periapical granulomas. In spite of the presence of the
IgE producing cells the morphological picture of mast cells did not suggest the presence of
anaphylactic reaction in periapical lesions. Diffuse distribution of T lymphocytes, moreover with the prevalence of T-suppressor/cytotoxic over T-helper lymphocytes and not numerous macrophages in the inflammatory infiltrates did not suggest the participation of a typical cell-mediated immunity reaction in the development of
periapical granulomas. Numerous T-suppressor/cytotoxic lymphocytes and low numbers of macrophages can be important factors of the chronicity of periapical inflammatory diseases.