Inhibition of in vitro lymphocyte function by a soluble AKR leukemic suppressor factor.

Area of Science:

• Immunology
• Cancer Biology
• Cellular Immunology

Background:

• Soluble suppressor factors in leukemia can impact immune responses.
• AKR mice with lymphocytic leukemia produce factors inhibiting spleen cell proliferation.

Purpose of the Study:

• Characterize the in vitro biological activity of leukemic mouse serum (LMS).
• Investigate the effects of LMS on mixed lymphocyte reactions (MLC) and cytotoxic T lymphocyte (CTL) generation.

Main Methods:

• In vitro assays measuring spleen cell proliferation.
• Mixed lymphocyte reactions (MLC) to assess CTL generation.
• Cytotoxicity assays for CTL and NK cell activity.
• Time-course addition of LMS during MLC.
• IL-2 addition assays in PHA proliferation tests.

Main Results:

• LMS inhibits spleen cell proliferation and CTL generation in MLC across various H-2 haplotypes.
• LMS does not affect established CTL or NK cell-mediated cytolytic activity.
• Suppression by LMS is reversible upon restimulation of responder cells.
• LMS inhibits early stages of CTL generation (Day 0-1) but not later stages (Day 2-4).
• IL-2 addition does not overcome LMS-induced inhibition in PHA proliferation assays.

Conclusions:

• LMS inhibits lymphocyte proliferation and early CTL generation.
• The suppressive mechanism may involve impaired IL-2 binding or utilization rather than IL-2 deficiency.
• LMS affects lymphocyte activation but not effector functions like cytotoxicity.