In Vitro Modulation of Lymphokine - Activated Killer (Lak) Cell Function by Aqueous Suspensions of Inert Particles

Aqueous suspensions of inert particles were shown to inhibit the natural killer (NK) cell and lymphokine - activated killer (LAK) activity of peripheral blood mononuclear cells (PMBC) and large granular lymphocytes (LGL). This inhibition was induced with both latex and silica particles. The inhibition of cytotoxic cell function was not related to effector cell death as determined by trypan blue exclusion, but appeared to be more specific for NK cell function (45.6 ± 4.5 % suppression of baseline NK cell activity) than LAK cell function (10.3 ± 3.4 % supperssion of baseline LAK cell activity) when the effector cells were preincubated with latex particles for 4 hours (p<0.05). Greater inhibition of LAK activity (35.6 ± 5.4% suppression) could be obtained if the efector cells were incubated with the particles during the 72 hr IL - 2 incubation period. In all tests, silica particles appeared to be more potent in suppressing cytotoxic activity than did particles of latex. Glass adherent monocytes which were incubated with purified LGLs did not accentuate particle-induced suppression, suggesting that monocytemediated suppression was not a major mechanism in the induction of these abnormalities. These studies indicate that exposure to small particles may directly suppress NK cell and LAK cell function and could contribute to an impaired ability of the host to resist tumor growth.