Toxocara canis infection reaches the lungs in paratenic hosts. The aim of this work was to evaluate changes in lung eosinophil and mast cell (MC) populations in experimentally infected BALB/c mice.
Six groups (ten animals each) were used. Three of them were orally infected with 1500 T. canis eggs and the other three received just saline. One of each group was killed at days 5, 30 and 60 after infection (PI). Histological samples from these lungs were stained using haematoxylin-eosin, toluidine blue and Chromotrope 2R dyes. The density (cells/mm2) of eosinophils and mast cells at the interstitial, perivascular and peribronchial regions were recorded using a computer assisted image analyzer.
Peribronchial (5d PI) and perivascular (60d PI) increases in MC were statistically significant in infected animals (P<0.05). In these animals, eosinophils increased at the interstitial (days 5, 30 and 60 PI), perivascular (60d PI) and peribronchial (60d PI) regions (P<0.05).
Results showed that the parasite induced a strong eosinophilic reaction within the tissue at days 5 and 30 PI and it was less evident by d60, perhaps due to immunoevasive mechanisms and the larvae migration. This migration may induce the perivascular and peribronchial cell infiltration also detected by these times. A MC infiltration was also induced in infected animals, but a regular pattern of infiltration was not shown, possibly due to cell degranulation, making difficult the MC detection. A Th2 type immune response may be involved in the recruitment of these inflammatory cells, possibly through the release of IL-4 and IL-5. This type of changes in inflammatory cells in the lung may predispose to allergic reactions as suggested in asthmatic humans.
Proyecto PAPIIT IN-212501