Lactoferrin-inducible monocyte cytotoxicity for K562 cells and decay of natural killer lymphocyte cytotoxicity.
Monocyte-enriched and lymphocyte-enriched fractions of peripheral blood from three healthy volunteers were obtained by percoll density gradient centrifugation. The cytotoxic activity of each fraction against 51Cr-labelled K562 cells was quantified in a 2-h assay using freshly isolated cells of each fraction and cells of each fraction which had been incubated with and without lactoferrin in complete medium for 18 h before performing the assay. We have thereby shown that cytotoxicity was not demonstrable in the lymphocyte fraction (containing 7.3 +/- 2% large granular lymphocytes) after 18 h in medium, whereas the cytotoxicity of the monocyte fraction (containing 3 +/- 0.4% large granular lymphocytes) was still significantly increased (P less than or equal to 0.01) and that lactoferrin had no effect on lymphocyte fraction cytotoxicity while producing an 11-fold increase in the cytotoxicity of the monocyte fraction. It is therefore possible to perform a relatively simple test of monocyte cytotoxicity using lactoferrin as a stimulant in a 2-h 51Cr-labelled K562 assay system by allowing 18 h to elapse for lymphocyte natural killer cytotoxicity to decay.
McCormick
J A
JA
Department of Haematology, Belfast City Hospital, Northern Ireland.
Markey
G M
GM
Morris
T C
TC
D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects*; D007781:Lactoferrin / Q000494:pharmacology*; D009000:Monocytes / Q000187:drug effects / Q000276:immunology*; D014407:Tumor Cells, Cultured
D007781:Lactoferrin