Diagnosis of congenital toxoplasmosis in the neonatal period: A multicenter evaluation.

OBJECTIVE: To evaluate different laboratory tests used to diagnose congenital toxoplasmosis in the neonatal period. STUDY DESIGN: A retrospective multicenter study of 294 pregnant women who experienced seroconversion for Toxoplasma gondii and subsequently delivered live-born infants. Fetal infection was assessed via specific IgM and IgA antibodies (cord and neonatal blood) and detection of T gondii in placenta and cord blood by mouse inoculation. RESULTS: Ninety-three (32%) of the 294 infants were congenitally infected. The sensitivity of IgA in cord blood and in neonatal blood was 64% and 66%; the sensitivity of IgM was 41% and 42%, respectively. Mouse inoculation of the placenta and cord blood had sensitivities of 45% and 16%. Positive results of the serologic tests in congenitally infected children correlated significantly with the gestational age at the time of maternal infection but was not significantly influenced by the administration of specific antiparasitic treatment during pregnancy. CONCLUSION: Specific T gondii IgA antibody is a more sensitive test than IgM for detecting congenital toxoplasmosis in the neonatal period. The overall specificity is better for serologic tests performed on neonatal blood than for those on cord blood. Neonatal screening with IgM or IgA antibodies will not detect the majority of children with congenital toxoplasmosis when the maternal infection occurred before the 20th week of pregnancy.

Bradykinin-induced tyrosine phosphorylation of proteins in cultured human keratinocytes.

The stimulating effect of bradykinin on phosphorylation of proteins at tyrosine residues was visualized on human keratinocytes in primary culture. Keratinocytes were subjected either to short-time (30 s) or to long-time stimulation (4 h) with 200 nM bradykinin. Especially keratinocytes of the G1 phase showed bright immunofluorescence with monoclonal anti-phosphotyrosine antibody. Solubilized membrane proteins were fractionated by gel filtration and tested for tyrosine phosphorylation by ELISA. Short-time stimulation induced a broad peak with a shoulder at 90 kDa, the main peak at about 60 kDa and a second shoulder at 44 kDa. After long-time stimulation an additional distinct peak at 180 kDa appeared, phosphorylation at 90, 60 and 44 kDa was less pronounced. Tyrosine phosphorylated proteins were further characterized by SDS-polyacrylamide gel electrophoresis, Western blotting and detection by monoclonal anti-phosphotyrosine antibody. After short-time stimulation with bradykinin tyrosine phosphorylation was confined to distinct bands at 82, 76, 70, 57, 54, 48, 40 and 39 kDa and a diffuse band at 62 kDa. After long-time stimulation tyrosine phosphorylation increased for the 76 kDa band and the bands at 48 and 40 kDa became more diffuse, the 39 kDa band remained and the others disappeared. Among these proteins, MAP kinase, actin, paxillin and the EGF receptor were the most likely candidates for bradykinin-induced tyrosine phosphorylation. Therefore, these effects in keratinocytes might be associated with events related to mitosis, adhesion and variation in cell shape.

Demonstration of acrosomal membranes using the hypo-osmotic swelling test.

The state of the acrosomal membranes in human spermatozoa was studied by means of the hypo-osmotic swelling test and indirect immunofluorescence using anti-boar outer acrosomal membrane antibodies. The swelling phenomenon observed in the acrosomal region was characterized by expansion of the plasma membrane without modification of the outer acrosomal membrane.

Monocyte suppression of antigen-specific lymphocyte responses in diffuse cutaneous leishmaniasis patients from the Dominican Republic.

Patients from the Dominican Republic with diffuse cutaneous leishmaniasis showed in vivo and in vitro anergy to leishmanial antigen. Relatives of these DCL patients living in the same endemic area frequently showed skin test and lymphocyte reactivity to leishmanial antigens. This further supports the concept of specific anergy in patients with diffuse cutaneous leishmaniasis. Adherent suppressor cells modulate the antigen-specific lymphocyte proliferative response. Suppressor cells could also be isolated by Percoll gradient centrifugation. Co-culturing of lymphocytes and monocytes from HLA-identical leishmanin responders and nonresponders also identified the suppressor cell as a monocyte. In one patient, this suppression disappeared when clinical cure had been accomplished.