Data collection and analysis for an in vitro cytotoxicity validation study

JA Strickland¹, MW Paris¹, H Raabe², J Haseman¹, S Casati³, R Clothier⁴, C Cao⁵, P Crockett⁶, RR Tice¹, WS Stokes⁷

1. ILS, Inc., NIEHS/NICEATM, RTP, NC, USA
2. IIVS, Gaithersburg, MD, USA
3. ECVAM, JRC, Ispra, Italy
4. Univ. of Nottingham, Nottingham, United Kingdom
5. U.S. Army ECBC, Aberdeen Proving Ground, MD, USA
6. Constella Group, Durham, NC, USA
7. NIEHS, NICEATM, RTP, NC, USA

A multi-laboratory validation study designed by NICEATM and ECVAM evaluated two in vitro basal cytotoxicity test methods using 72 coded chemicals with a wide range of acute oral toxicity. The study was designed in three phases to allow for refinement of the protocols, and data collection and evaluation procedures. An Excel® template was distributed to the participating laboratories for entry of the raw data, identification of outliers among the six concentration replicates, documentation of materials and procedures, graphical analysis of dose-response, and formatting of data for further analysis. A Hill function analysis with GraphPad Prism® software was used to calculate IC20, IC50, and IC80 values and associated 95% confidence limits, and graph the data and fitted model. Initial criteria for an acceptable dose-response for individual tests included one data point between 10 and 50% viability, one data point between 50 and 90% viability, and r2 ≥ 0.8. A Prism® template was distributed to the laboratories to automate and provide uniformity of analysis. To increase the speed of data collection and evaluation by the Study Management Team (SMT) and consulting biostatisticians, the laboratories submitted the Excel® and Prism® files by e-mail. Results compiled by the SMT were returned to the originating laboratories for audit to ensure accurate transmission of data. Implementation of these procedures demonstrated that automated data collection in relatively common, easy-to-use electronic formats facilitates uniformity of data collection and analysis. Supported by: N01-ES 35504; EPA IAG DW-75-93893601-0; European Commission 19416-2002-04 F2ED ISP GB.

P188

Date: Tuesday, August 23, 2005, 13.00-14.00 h

5.6 Session: In Vitro Aproaches for Determining Acute Systemic Toxicity.