[A new agglutination reaction for the diagnosis of the developmental stage of acquired toxoplasmosis].

Agglutination of acetone treated toxoplasma (AC) is different from that one of formalin fixed parasites (HS). Sera from patients with a recently acquired ("acute") infection agglutinate both HS and AC parasites suspensions as well; contrary to sera from patients with past infection ("chronic stage") in which high titers of HS agglutination are often present, while the titres of AC agglutination are lower even negative. This is markedly observed in patients with local lesions (relapsing chorioretinitis, patients with AIDS and brain abscesses). The reason might be that different membrane toxoplasma antigens may induce the synthesis of agglutinating IgG. For example, antigens 35 KD and 27 KD described by E. Handman et al. The antibody specific for 27 KD is apparently present mainly during acute infection, contrary to the antibody specific for 35 KD which might be responsible of the high HS agglutination titre in sera from patients with chronic infection. Even if these hypotheses were not confirmed in the future, comparison of the titre in the HS and AC agglutination test might actually be helpful for practical diagnosis of the stage of toxoplasma infection.