Total IgA and Porphyromonas gingivalis-reactive IgA in the saliva of patients with generalised early-onset periodontitis

Generalised early-onset periodontitis (GEOP) is characterized by acute infl ammatory bursts, resulting in rapid destruction of the periodontal apparatu s in young adults. An impaired host defense seems to play an important role as etiological factor of periodontitis, especially in the development of G EOP. As the Gram-negative Porphyromonas gingivalis has been identified as o ne of the causative anaerobic bacteria, the humoral immune response to this micro-organism is of particular interest in patients with GEOP. To evaluat e the local immune status, we measured total and P. gingivalis-reactive sal ivary IgA in GEOP patients and in age- and gender-matched periodontally nor mal controls. We found a significantly lower concentration and secretion ra te of total salivary IgA in the GEOP group. Although no differences were de tected in the concentration or secretion of P. gingivalis-reactive IgA betw een groups, the specific fraction of P. gingivalis-reactive IgA of the tota l IgA was significantly higher in the GEOP group. These findings indicate a n inhibition of total secretory IgA in GEOP, while the P. gingivalis-reacti ve humoral immune system in saliva is, however, activated. P. gingivalis se ems to selectively activate IgA lymphocyte clones and induces a switch in t he fraction of specific IgA.