Predictive value of Toxoplasma gondii antibody titres on the occurrence of toxoplasmic encephalitis in HIV-infected patients. ANRS 005/ACTG 154 Trial Group.

OBJECTIVE: To study the predictive value of anti-Toxoplasma gondii antibody titres for the occurrence of toxoplasmic encephalitis (TE) in HIV-infected patients. METHODS: Data from the placebo arm of a trial of primary prophylaxis for TE (ANRS 005/ACTG 154) were analysed. Patients included had CD4+ cell counts < 200 x 10(6)/l and a positive Toxoplasma serology. Immunoglobulin (Ig) G and IgM Toxoplasma antibody titres at entry were retrospectively determined by enzyme-linked immunosorbent assay and agglutination on serum samples in a single laboratory. Incidence of TE was estimated by Kaplan-Meier method and a Cox model was used to study the predictive value of antibody titres, adjusted for other covariates. RESULTS: All 164 patients studied were positive for IgG antibodies and one had IgM antibodies. After a mean follow-up of 16 months, 31 cases of TE were documented. One-year incidence of TE was significantly higher in patients with IgG titres > or = 150 IU/ml (23.7%) than in patients with titres < 150 IU/ml (7.7%; relative risk, 3.1; P < 0.003). IgG titres remained significantly associated with the occurrence of TE (relative risk, 3.3; P < 0.005) in the Cox model. Predictive value of IgG titres did not differ according to baseline CD4+ cell counts. CONCLUSIONS: In patients with CD4+ cell counts < 200 x 10(6)/l, IgG anti-Toxoplasma antibody titre is a prognostic factor of occurrence of TE, with a higher risk for titres > or = 150 IU/ml. This finding should reinforce the recommendation of specific prophylaxis in these patients.

Performance evaluation of the haematological analyser Cell-Dyn 3000 (Abbott).

The Abbott Cell Dyn (CD) 3000 is an automatic analyser, designed to give a complete blood count (CBC) and white blood cell differential (WBCD) by 4 angle diffraction analysis. This instrument was evaluated by comparison of results obtained with those obtained from a Technicon H1 analyser and by microscopic examination. Technical performances with regard to reproducibility, linearity and carryover was acceptable and in normal samples there was close correlation with the optical method (R > 0.9) for neutrophils (NE), lymphocytes (LY) and eosinophils (EO). Correlation for monocytes (MO) and basophils (BA) was poorer but without clinical consequences. Significant thresholds for immature granulocyte (IG) and variant lymphocyte (VL) flags were determined and using these thresholds the false positive rate was reduced to 7%. In haematological diseases, no false negatives were observed as all samples were flagged. However, since no case of acute lymphoblastic leukaemia (ALL) was studied, the detection of lymphoblasts which is known to present difficulties for analysers remains to be evaluated. Blasts in acute myeloblastic leukaemia (AML) and hairy cells were recognised, while in chronic lymphocytic leukaemia (CLL) it was possible to define 3 groups according to the flags released. The CD appears to be a satisfactory analyser for use in general or haematological laboratories performing a large number of WBCD per day.