Comparison of conventional cytomorphology, flow cytometry immunophenotyping, and automated cell counting of CSF for detection of CNS involvement in acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVE: Cytospin conventional cytomorphology (CCC) is the standard method for detecting lymphoblasts in cerebrospinal fluid (CSF) of patients with acute lymphoblastic leukemia (ALL) and for guiding treatment decisions. We evaluated flow cytometry immunophenotyping (FCI) performance for improving detection of central nervous system (CNS) involvement in ALL. METHODS: This prospective study included analysis of consecutive CSF samples of patients of all ages with ALL at 3 clinical stages: new diagnosis, relapse suspicion, and after relapse treatment. Manual, cytospin, automated, and FCI methods were compared and their performance statistically assessed. Using FCI as the reference method, optimal CSF cutoff cell count that better correlated with presence of lymphoblasts was established by receiver operating characteristic (ROC) curve analysis. RESULTS: Seventy-seven CSF samples were investigated, 35 (45.4%) from newly diagnosed cases, 30 (39%) suspicion of relapse, and 12 (15.6%) after treatment for relapse. Median manual WBC count in patients with CNS involvement detected by FCI was 3.75 cells/µL (0.0-1280), and this was also the count that best correlated with CNS infiltration (sensitivity, 50.0%; specificity, 82.2%). Compared with FCI, CCC sensitivity and specificity were 28.6% and 100%. Automated CSF WBC count in patients with CNS involvement detected by FCI was 5 (0.0-1578). For automated count, optimal WBC cutoff was 4.5 cells/µL (sensitivity, 62.5%; specificity, 70.5%). CONCLUSION: Flow cytometry immunophenotyping complements conventional cytospin analysis for detection of lymphoblasts in the CSF of ALL patients at any clinical stage.

Lung injury induced by antibody fragments to angiotensin-converting enzyme.

Rabbits given goat anti-rabbit angiotensin-converting enzyme antibodies or derived antibody fragments develop rapidly fatal pulmonary edema. Endothelial cell injury is manifested by bleb formation and the disintegration of cell membranes. Platelets are found along the injured endothelium and leukocytes block capillary lumens. The pathologic features are similar when immune IgG, F(ab')2, or Fab are given. In vitro studies of complement activation show that solubilized, purified angiotensin-converting enzyme alone activates C1, with consumption of C4 and C3. Addition of immune IgG plus converting enzyme enhances this activation. F(ab')2 plus enzyme enhances only C3 consumption, while Fab with enzyme produces no additional complement utilization. Thus, while complement activation may be involved in the pathogenesis of injury induced by IgG or F(ab')2, the mechanism of Fab-induced endothelial injury remains unclear.