Isotope-labelled alpha-amino-isobutyric acid as an indicator in cytotoxicity tests.

The effect of rabbit antisera on the uptake and release of alpha-amino-isobutyric acid (AIBA) in LS- and P-388 cells was investigated. In the presence of homologous antiserum and complement, the uptake of AIBA was inhibited. In the absence of complement, no effect of antiserum was seen. Using prelabelled cells, the efflux of AIBA was greatly accelerated in the presence of antiserum and complement. The AIBA-uptake method was compared with the trypan blue exclusion test and the 51Cr release technique. The AIBA-uptake method was more sensitive in quantitative cytotoxic studies.