Pulmonary and immune responses to a Thermoactinomyces vulgaris antigen respiratory sensitization in C57BL/6J mice.

Lung histology and immune responses were followed during a six month period of Thermoactinomyces vulgaris antigen respiratory sensitization of C57BL/6J mice. Histologically, the mice developed a picture resembling the subacute stage of human farmer's lung. At the early phase of the sensitization a T-cell response was seen in vitro, characterized by an increased spleen but no peripheral blood lymphocyte reactivity to T-cell mitogens at the same time as increased reactivity to the sensitizing antigen was detected. An increase in the percentage of T-cells in the lavage cell population was also seen. The sensitization was associated with the appearance of both IgG and IgA antibodies in lavage and in serum of which lavage IgA antibodies were found to follow the course of the sensitization most accurately. The increase in antibody titers was not, however, reflected in lavage cytology or in lymphocyte reactivity. The results suggest that different immunological reactions may be predominant at different stages of farmer's lung.