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The leukotoxin produced by Actinobacillus actinomycetemcomitans is considered the major virulence factor with potential to cause damage to the host defenses. The present work analyzed the serumal and salivary levels of antibodies against the leukotoxin produced by A. Actinomycetemcomitans, in patients with Localized Juvenile Periodontitis (LJP) and in healthy controls. Additionally, analysis of the immune complex (IC) was carried out in saliva samples. The classic ELISA method, with leukotoxin obtained through Sephadex G-200 gel filtration, and the capture ELISA method, using rabbit anti-A. Actinomycetemcomitans (leukotoxic, FDC Y4, IgG) adsorbed with a non-leukotoxic strain of A. actinomycetemcomitans, were used. The results obtained demonstrated significantly higher serumal levels of IgG in patients with LJP, when they were compared with the healthy controls, both for the classic and capture ELISA methods (p < 0.05). However, no significant differences were observed between the salivary levels of IgG, SIgA and IC in the examined individuals. These results suggest that even though A. actinomycetemcomitans presents virulence factors that affect the immune response, there is immune response to leukotoxin in LJP patients. This increase of IgG in the blood stream might contribute to host defense, limiting the lesion to the periodontal regions already colonized by A. actinomycetemcomitans.

Anti-human T lymphocyte serum specific to the receptor for sheep erythrocytes (E) was produced by immunizing sheep with autologous erythrocytes sensitized with solubilized receptors from human lymphocytes. The anti-soluble receptors serum (anti-Rs) inhibited E-Rosette formation, identified T lymphocytes by indirect immunofluorescence, agglutinated the formalized E-soluble receptors complexes, and inhibited the E-soluble receptors interaction. This anti-Rs serum was also submitted to the affinity chromatography by protein A sepharose, and the amounts of 0.15 to 120 micrograms of purified anti-Rs IgG were added to the lymphocyte culture. The result obtained showed an induction of proliferative response of the normal human lymphocytes in the presence of 60 and 120 micrograms of anti-Rs IgG.