The effects of coal and quartz (14808607) dusts on the immune system were studied in-vitro and in-vivo. Splenocyte cultures prepared from female PVG-rats were incubated with 0 to 100 micrograms per milliliter (microg/ml) anthracite (dust-A) or a low rank coal mine dust (dust-L), titanium-dioxide (13463677) (TiO2), or quartz dust. The effects on phytohemagglutinin (PHA) stimulated mitogenesis were determined. The supernatants were collected from rat splenocytes that had been incubated with 0 to 250microg/ml dust-A, dust-L, TiO2, or quartz dust and added to splenocytes from other untreated rats or to thymocytes from C3H-mice. The effects on PHA stimulated splenocyte mitogenesis were investigated. Induction of splenocyte supernatant interleukin-1 (IL1) was determined by measuring the extent of thymocyte proliferation. Female PVG-rats were administered 0 or 1 milligram dust-A, dust-L, TiO2, or quartz dust intratracheally and killed 7 days later and the lungs were removed and lavaged. The lavage fluid cells (BACs) were added to splenocytes from untreated rats and the effects on splenocyte mitogenesis were determined. The BACs from quartz treated rats were separated into the macrophage and neutrophil fractions and tested for their effect on splenocyte mitogenesis. Quartz and 10, 50, and 100microg/ml and dust-L at 50 and 100microg/ml significantly enhanced splenocyte mitogenesis. TiO2 and dust-A inhibited splenocyte mitogenesis in a dose dependent manner. Supernatants from dust treated splenocytes did not enhance splenocyte mitogenesis. The supernatant from quartz treated splenocytes revealed significant IL1 activity. BACs from dust-L, dust-A, and TiO2 treated rats had no effect on splenocyte mitogenesis. BACs from quartz treated rats significantly inhibited splenocyte mitogenesis. The macrophage enriched fraction inhibited splenocyte mitogenesis to a lesser extent, whereas the neutrophil enriched fraction significantly enhanced mitogenesis.