CHANGES OF THE LUNGS IN MICE INDUCED BY M IGRATION OF TOXOCARA-CANIS LARVAE

The influence of T. canis larvae migration on the lung tissue of parat enic host (inbred mice, strain C57BL6/J) was evaluated. First macrosco pic manifestation was already observed on day 2 in the time of the hig hest larval recovery. Larvae entering the lung tissue caused numerous small extravasations. Their migration from the lungs was manifested fr om day 6 with an increase in the number and extent of extravasations. The lungs assumed tiger spot appearance (Fig. 1). The larval recovery was decreasing. From day 14 the expressiveness of macroscopic changes was declining. Areas of emphysema and atelectasis were observed on the lungs. The genesis and the process of elimination of extravasations w ere studied histologically. In the first period, the primary extravasa tions, caused by larvae migrating to the lung tissue (Fig. 2), were el iminated by monocytes and eosinophilic granulocytes in increasing numb ers (Fig. 3). Immunohistochemically macrophages and dendritic cells we re already observed in the lungs on day 1 (Fig. 4). Acid phosphatase a ctivity was increasing from day I and its highest level was observed o n day 84. Alkaline phosphatase activity on days 2-4 was not observed i n the areas of extravasations although within the larvae themselves it was high. The extravasations of the second period (caused by larval m igration from the lungs) from day 5-6 were eliminated with humoral mon ocytes and cells of perivascular and peribronchial tissue. Eosinophils were not active in this process. Strong exudation was observed here. The humoral part of extravasations was eliminated primarily. The cytop lasmatic volume of activated cells was enlarging. Multinuclear symplas ms were originated (Fig. 5). The activities of alkaline phosphatase an d nonspecific esterase were increased. Macrophages and dendritic cells were still present in high numbers and from day 14 aggregations of T and B lymphocytes were observed (Fig. 6). Reparative processes were fr equently observed on the blood vessels altered by the leaving larvae ( Fig. 7). Changes on the lungs caused by migration of larvae always end ed in functional regeneration of the lung tissue. On the other hand de ad larvae stimulated proliferative forms of inflammatory reactions whi ch led to induration (Fig. 8).