SCIENCE@home

Kinetic analysis of human spontaneous cell-mediated cytotoxicity.

S. Pollack,S. L. Emmons

Published 1979 in Journal of Immunology

ABSTRACT

We tested whether the kinetics of human spontaneous cell-mediated cytotoxicity (SCMC) fit the enzyme-substrate model for cellular cytotoxicity. As predicted by the model, the maximal rate of killing (Vmax) was proportional to the number of effector cells added, whereas the apparent affinity constant, K1/2, was a function of the source of effector cells, and remained unchanged when the number of effector cells was doubled. The linear initial velocity of lysis was maintained for only 90 min; thereafter, lysis proceeded at a lower rate. Thus the model strictly applies only during the initial phase. Two lines of evidence suggested that NK cells that mediate SCMC function as recycling catalysts. Zone analysis of the log-dose relationship for SCMC indicated that effector cells are present in negligible amounts compared to the substrate. Although the rate of killing decreased with time, it appeared that each NK cell killed more than one target. When the same effector cell population was tested on two different targets, K562 and Chang, different K1/2 values were obtained. This result suggested that the two cell types are recognized differently, e.g., because they bear different determinants. Finally, we demonstrated formally that immune complexes competitively inhibit SCMC. If the enzyme-substrate analog holds, then FcR on NK cells are implicated either to be the “active site” for SCMC or to be closely linked to the active site.

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-23 of 23 references · Page 1 of 1

CITED BY

Showing 1-42 of 42 citing papers · Page 1 of 1