Neosynthesized IgG detected by Western blotting in Toxoplasma-seropositiveheart or lung transplant recipients

Toxoplasmosis is a life-threatening disease in heart- or lung transplant re cipients that can result either from the reactivation of a latent infection or from an organ-transmitted infection. The diagnosis of acute toxoplasmos is is easy in cases of seroconversion following a mismatch. However, when t he recipient is Toxoplasma-seropositive before transplantation, usual serol ogical techniques do not allow the differentiation between endogenous and o rgan-related reinfection. The aim of this study was to determine whether we stern blotting could contribute to this differentiation. Sequential sera fr om two heart- and one liver- and lung transplant patients whose anti-Toxopl asma antibody titers strongly increased after transplantation, were analyze d by western blotting. Neosynthesized IgG were observed on blots incubated with the sera from two patients who had received transplants from Toxoplasm a-seropositive donors, whereas no neosynthesized IgG was detected on blots from the patient who had received a transplant from a Toxoplasma-seronegati ve donor. Our results suggest that the detection of neosynthesized IgG in t he recipient may be related to the recognition of a new parasite strain pos sibly brought by the transplant from a Toxoplasma-seropositive donor.