title: The maximum conjugate frequency (alpha max) characterizes killer cell populations.
abstract: A quantitative procedure to characterize NK cell populations based on the dependence of the frequency of conjugation (alpha) on the effector-to-target ratio (R) is shown. To this end, a detailed study of the influence exerted by: (a) the value of R; (b) the number of effector and target cells (N, T); and (c) the source (donor) and enrichment of the effector cell population on the frequency of conjugation between NK effector and K562 target cells has been performed. This has demonstrated that for a given value of R large differences in the values of alpha can be obtained for different donors and/or N values. Hence, the usual practice of reporting the frequency of conjugation at a given value of R cannot be used as a valid criterion for comparison, and this could explain the differences in the alpha values reported in the literature for the same effector-target system. Moreover, the frequency of conjugation depends on the enrichment of the effector cell populations, although it has been shown that in all cases a plot of 1/alpha vs. R for N = constant is always linear with intercept 1/alpha max.alpha max represents the maximum frequency of conjugation for an effector-target system and remains constant for all values of R and N, and is also independent on the donor of the cell source. These characteristics make that the values of alpha max can be used as an easy criterion to determine with accuracy conjugate frequencies in an effector-target system, and could also be applied to characterize the activation or inhibition of effector cell populations by monoclonal antibodies or other agents. This criterion was applied to characterize the enrichment of NK cell populations and so, a value of alpha max = 58 +/- 3% has been obtained when highly purified (greater than or equal to 99%) NK effector cells obtained by panning with the monoclonal antibodies Leu-2, Leu-3 and Leu-4 are used. However, the corresponding value for MDC (14% NK cells) was lowered to 26 +/- 1%.
authors.affiliation: Department of Medicine, School of Medicine, University of New Mexico, Albuquerque 87131.
authors.forename: P
authors.initials: P
authors.lastname: Garcia-Peñarrubia
authors.forename: F T
authors.initials: FT
authors.lastname: Koster
authors.forename: A D
authors.initials: AD
authors.lastname: Bankhurst
mesh_terms: D000328:Adult; D002448:Cell Adhesion; D002450:Cell Communication; D002460:Cell Line; D002469:Cell Separation; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods; D003602:Cytotoxicity, Immunologic; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000145:classification* / Q000276:immunology; D004915:Leukemia, Erythroblastic, Acute / Q000276:immunology; D008297:Male; D011237:Predictive Value of Tests