Apr 1, 1976

Characterization of cells that suppress the cytotoxic activity of T lymphocytes. I. Quantitative measurement of inhibitor cells

The Journal of Immunology : Official Journal of the American Association of Immunologists
D A ClarkR G Miller


Target cell lysis by sensitized cytolytic T lymphocytes (CTL) may be conveniently quantitated by 51Cr release. By fitting to the formula, P (% specfic release) = 100 (1-e-Nat) one obtains alpha, the relative frequency of CTL in N lymphoid cells. Using a microassay and murine sarcoma target cells, we observed an unexpected decrease in lysis whenever effectors obtained from a graft-vs-host reaction were tested at high concentrations. This inhibition was not observed with CTL generated by an MLC reaction. Inhibition could not be explained by nonspecific mechanical 'crowding', reutilization of released isotope, suppression of release from dead target cells, or the particular strain combination and target used. By modifying the formula to allow suppression of CTL by a stochastic cell-cell interaction with suppessor cell, we found that P = 100 (1-e-Nate-Ngamma) adequately fitted the data, where Ngamma is proportional to inhibitor content. An 18- to 24-hr incubation at 37 degrees C but not 4 degrees C allowed selective depletion or enrichment of inhibitors; in mixing experiments, both parameters Nalpha t and Ngamma behaved stoichiometrically as independent cellular properties. The inhibitor was resistant to concentrations of anti-T ce...Continue Reading

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Mentioned in this Paper

Lymphocyte Culture Test, Mixed
Tumor Lysis Syndrome
Graft Vs Host Reaction
Sarcoma, Jensen
Therapeutic Immunosuppression
Chromium Radioisotopes
Microcytotoxicity Test

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