Immunology of clinically inactive sarcoidosis: serum factors.

Sera from 84 white patients with inactive sarcoidosis were analyzed for immunoglobulins, complement, autoantibodies, alpha 1-antitrypsin and lysozyme. The levels of serum factors were compared with levels in serum from a reference population which was matched for age, sex, ethnic background and geographic location. IgG, IgA, IgD, and C3 levels were similar for both groups, as were frequencies of rheumatoid factor, antinuclear antibody and anti-DNA antibody. Lysozyme levels were significantly lower in the inactive sarcoidosis group but the acute phase reactants alpha 1-antitrypsin, IgM as well as complement consumption were increased. The data suggest that the underlying etiological events of sarcoidosis continue, albeit at a subclinical level.

In vitro activation of the alternative pathway of complement by settled grain dust.

Settled grain dust was collected from several active grain elevators in the Superior-Duluth areas of the United States. Particle size distribution (47% less than 5 micrometer) and endotoxin contamination (429 ng/gm) of the dust were similar to those reported for the airborne parent dust. Human complement uas activated in vitro in a dose-response manner which could be quantified. This hemolytic consumption was via the alternative pathway as defined by ethylenediaminetertraacetic acid/ethylene-glycol-bis-(beta-amino-ethyl ether) N,N'-tetraacetic acid (EDTA/EGTA) differential serum chelation, factor B conversion, and complement reductions in serum from guinea pigs deficient in C4. It is proposed that continuous low-dose exposure to aerosolized, biologically active rafter dust could contribute to the respiratory insult of grain workers.

Activation of the alternative pathway of complement by grain. I. C3PA conversion and quantification of complement consumption by rye.

Ground whole rye and airborne rye dust of comparable size distribution were tested for their ability to activate the complement cascade via the alternative pathway. Precipitin-negative pooled normal human serum was incubated with increasing amounts of the two rye dusts. Electrophoresis of the resultant supernatant fluids demonstrated the conversion of the proactivator of the third component of complement to the gamma-migrating activator of the third component. This activation was completely prevented by pre-treating the serum with the chelator EDTA, while pre-treatment with EGTA allowed suboptimal arc conversion, strongly implying that complement was activated via the alternative pathway. Quantification of the supernanant fluids showed dose-dependent complement consumption as defined by both CH100 immunodiffusion and CH50 tube haemolytic techniques. Airborne rye dust showed a greater quantitative potential than ground whole rye for activating the alternative pathway. These results indicate the possibility of the direct action of airborne organic dusts on the induction of inflammatory sequelae in the lungs of both sensitized and unsensitized individuals.