Semiquantitative estimation of Shigella antigen-specific antibodies: correlation with disease severity during shigellosis.

Systemic and mucosal antibody responses during shigellosis were analysed and correlated with clinical severity. Patients infected with Shigella dysenteriae type 1 (SDIP), and S. flexneri (SFIP) were grouped according to disease severity. The disease was more severe in SDIP than in SFIP. Higher levels of Shigella antigen-specific serum antibodies were associated with severe disease. In contrast, decreased serum levels of IgG, IgM and total protein were associated with severe disease. Faecal levels of total IgA, secretory IgA, albumin, and LPS specific s-IgA were increased in severe disease. The results of the study indicate that the level of humoral immune response correlates with the disease severity in shigellosis and that the local immune system in the mucosa is directly engaged in the response. This is also reflected at the systemic level by increased serum levels of specific antibodies and non-specific inflammatory parameters.