Beryllium-stimulated in vitro migration of peripheral blood lymphocytes

Inhalation of beryllium (Be) induces both inflammatory and metal antigen-sp ecific immune responses in the lungs characterized by mononuclear cell infi ltration and granuloma formation (chronic beryllium disease, CBD). We teste d the hypothesis that Be-salts might increase the in vitro migration of per ipheral blood mononuclear cells (PBMC). PBMC are mixed cells, consisting of lymphocytes and monocytes. We compared their responses to populations of b oth purified blood lymphocytes, and purified blood monocytes. Purified bloo d monocytes and lymphocytes, isolated by Percoll gradients and centrifugal elutriation from normal human subjects (n = 6), were exposed to graded conc entrations (0.01 to 100 mu M) of BeSO4 or to the control metal-salt Al-2(SO 4)(3). Migratory responses of stimulated PBMC were measured in Boyden Chamb ers. As controls, PBMC mixed cells or purified lymphocytes or purified mono cytes were unstimulated or stimulated with a positive chemoattractant, Zymo san-A treated pooled, normal human serum (ZAS). The migration index (MI) wa s defined as the distance (micrometers) that cells migrated through a 5 mu filter. The MI for unstimulated PBMC mixed cells was 75 +/- 4 whereas the M I for ZAS-stimulated PBMC mixed cells was 124 +/- 4 (P less than or equal t o 0.05, Tukey-Kramer). The MI for BeSO4 -stimulated (100 mu M) PBMC mixed c ells was 136 +/- 4. The observed increase in the BeSO4-stimulated PBMC mixe d cell migration was significant down to 0.1 mu M BeSO4. BeSO4, BeCl2 and B eF2, tested at 100 and 10 mu M, were equally effective at inducing PBMC mix ed cell migration. Equimolar concentrations of Al-2(SO4)(3) were not as eff ective at inducing PBMC mixed cell migration, MI < 100 at 100 mu M, and did not induce PBMC mixed cell migration at concentrations below 1 mu M The mi gration of purified monocytes through filters was not increased in response to either BeSO4 or Al-2(SO4)(3), compared to controls, but did respond to ZAS (MI = 100 +/- 4). Purified lymphocytes migrated in response to stimulat ion with all concentrations of BeSO4 tested (100 mu M MI = 133 +/- 9), and Al-2(SO4)(3) (100 mu M MI = 85 +/- 8). There were no significant difference s in the MI for PBMC mixed cells or for purified lymphocytes at the concent rations of BeSO4 tested. Our data show that Be directly induces the in vitr o migration of PBMC mixed cells and purified blood lymphocytes, and not pur ified blood monocytes, across a broad range of Be concentrations. This indu ction of migration was independent of the molecular form of the Be-salt. In haled Be, by promoting lymphocyte emigration to the lung, may create a micr oenvironment that favors a Be-antigen-specific T-lymphocyte response, chron ic inflammation, and CBD. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.