EFFECTS OF VANADIUM UPON POLYI:C-INDUCED RESPONSES IN RAT LUNG AND ALVEOLAR MACROPHAGES

Abstract

Hosts exposed to vanadium (V) display a subsequent decrease in their resistance to infectious microorganisms. Our earlier studies with rats inhaling occupationally relevant levels of V (as ammonium metavanadate, NH₄V0₃) indicated that several nascent/inducible functions of pulmonary macrophages (PAM) were reduced. In the present study, V-exposed rats were examined to determine whether some of the same effects might also occur in situ. Rats were exposed nose-only to air or 2 mg V/m3 (as NH₄VO₃) for 8 h/d for 4 d, followed, 24 h later, by intratracheal (it) instillation of polyinosinic.polycytidilic acid (polyhC) or saline. Analysis of lavaged lung cells/fluids after polyhC instillation indicated that total lavageable cell/neutrophil numbers and protein levels, while significantly elevated in both exposure groups (as well as in saline-treated V-exposed rats), were always greater in V-exposed hosts. Exposure to V also affected the inducible production of interleukin 6 (IL-6) and interferon γ (IFNγ), but apparently not that of tumor necrosis factor-α(TNFα) or IL-1. Although polyl:C induced significant increases in lavage fluid IL-6 and IFNγ levels in both exposure groups, levels were greater in V-exposed rats. If calculated with respect to total lavaged protein, however, V-exposed rats produced significantly less cytokine. Following polyl:C instillation, there were no marked exposure-related differences in basal or stimulated superoxide anion production by pooled lavaged cells or PAM specifically. With V-exposed rats, pooled cells recovered 24 h after saline instillation displayed reduced production (in both cases) compared to the air control cells; PAM-specific production was affected only after stimulation. In both exposure groups, polyl:C caused decreased superoxide production in recovered cells. Though less apparent with pooled

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Mitchell D. Cohen

Address correspondence to Dr. M. D. Cohen, Nelson Institute of Environmental Medicine, New York University, Long Meadow Road, Tuxedo, New York, NY 10987, USA. E-mail: [email protected]