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Rats were administered with quartz dust intratracheally or subjected to chronic inhalation of the dust. Peroral overloading of rats with fat was shown to increase an accumulation of all lipid fractions in lungs and intensified silicotic fibrinogenesis. Similar alterations in lipid metabolism of lungs were observed in control animals maintained without the dust treatment at the same fatty diet; but these patterns were less distinct and were not accompanied by an increased collagene formation. Alterations in content of lipids in liver tissue and in blood did not depend on the dusting of lungs under fatty loading. Within the later period of inhalational dusting the increased accumulation of quartz was observed in lung tissue of rats maintained at fatty diet. The data obtained suggest that the recommended by some investigators increase in content of fats in miner's diet is not justified.

The adaptation of the alveolar phagocytosis response to the quantitative and qualitative features of dust deposited during inhalation consists not only in enhanced recruitment of alveolar macrophages (AM), but also in adding a more or less pronounced neutrophil leukocyte (NL) recruitment as an auxiliary participant of particle clearance. The NL contribution to clearance is especially typical for response to cytotoxic particles (quartz, in particular). An important feature of the adaptation considered is the limitation of the number of AM and NL recruited when an efficient clearance can be achieved by a lesser number of cells due to increased AM reistance to the damaging actin of phagocytized particles. The main mechanism providing the adequacy of the alveolar phagocytosis response is its self-regulation thrugh the products of macrophage breakdown (PMB). In a series of experiments with intraperitoneal and intratracheal injections of syngenetic PMB into rats and mice, it was shown that these products stimulate respiration and migration of phagocytic cells, their dose-dependent attraction to the site of PMB formation with the predominant NL contribution, increasing with the increase of amount of PMB, the AM and NL precursor cells recruitment from reserve pools, and the replenishment of these reserves in the process of hemopoiesis. At least some of the above effects are connected with the action of the lipid components of PMB. The action of specialized regulative systems of the organism can modify the response to PMB, judging by the results obtained by hydrocortisone injection. Autocontrol of alveolar phagocytosis requires great care in attempts at artificial stimulation of this process, as an excessive cell recruitment may promote the retention of particles in lungs.

A diet with low fat content did not influence the lipid level in the lungs and fibrinogenesis values in the development of silicosis in rats, due to the intensification of the lung lipopexic function, that was revealed in the prefibrosis period, using single fat load. A direct correlation of the lung lipopexic function degree in the prefibrosis period with the degree of pneumophibrosis developing afterwards was noted. The optimum time for the study of the rat lung lipopexic function was specified (1.5 h) after single fat load. It is recommended that the lung lipopexic function, as an indirect sign of the degree of the development of proliferative-cellular reactions in the lungs, be investigated in subjects engaged in the work associated with the risk of pneumoconiosis.

With a long-term (1 and 4 months) introduction of an additional amount of edible fats (beef, hog fats, butter, sunflower seed oil) to intact and intratracheally quartz-dust laden sexually mature male rats an organ-specific reaction to the supply of fat, and in intact rats, also some peculiarities of the reaction depending upon the kind of the introduced fats, were discovered. An additional administration of fats to rats with developing silicosis tended to increase accumulation of lipids in the lungs and led to a higher content of oxyproline in the lungs and liver, which bears proof to an adverse effect produced by the introduced fats on the lipids metabolism and the processes of silicotic fibrogenesis.