Divalent cations and cytochalasin B-sensitive processes in activation, synthesis, and release of mixed leukocyte reaction suppressor factor

Academic Article


  • We have examined the possible rotes of divalent cations and of cytochalasin B-sensitive processes in the production of mixed leukocyte reaction suppressor factor (MLR-TsF). Ca but not Mg was strictly required for MLR-TsF production. A requirement for Mg could be demonstrated only under conditions of Ca depletion, suggesting an intimate linkage in divalent cation requirements. Ca was required for synthesis as well as release of the suppressor factor. Cytochalasin B inhibited MLR-TsF production only when present during the first 4 hr of culture; such inhibition was reversible with incubations of up to 16 hr. This indicated that cytochalasin B inhibited early events of activation, rather than synthesis or release of MLR-TsF. It was found that both Ca and Mg were required either before or during the cytochalasin-sensitive steps in the activation sequence. The relationship of cytochalasin B-sensitive events in early activation to the antigenic stimulus per se was established by limited exposure of suppressor cells to allogeneic stimulators fixed to poly-l-lysine (PLL)-coated plates. Maximal stimulation was observed with a 4-hr exposure, and this antigen-dependent commitment was cytochalasin B sensitive. © 1981.
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    Author List

  • Belmont JW; Rich RR; Rich SS
  • Start Page

  • 353
  • End Page

  • 364
  • Volume

  • 61
  • Issue

  • 2