Experimental Hypersensitivity Pneumonitis: Suppressor Cell Influences

Abstract

Experimental hpersensitivity pneumonitis (EHP) can be transferred to strain 2 guinea pigs by lymph node cells (LNC) cultured in vitro with antigen. Using mixtures of cell populations, we sought to determine if functional suppressor cells were present in our system. We also characterized the composition of cell populations that were capable (blast 10 μ/mL Micropolyspora faeni from 2-week donor animals) and incapable (blast 0 μg/mL M. faeni from 2-week donor animals; blast 10 μg/mL from 8-week donor animals) using flow cytometry, anti-Ig and monoclonal antibody 8BE6 (T cell marker) of transferring EHP. Two groups of donors were used: animals sensitized with Freund's adjuvant and M. faeni and challenged with either two or eight weekly intratracheal (IT) injections of M. faeni (2- and 8-week groups). LNC from donor animals were cultured with a soluble extract of M. faeni (10 or 0 μg/mL) blasts isolated and transferred IV to syngeneic recipients. Control animals received media IV. Recipients were challenged IT with M. faeni 48 h after the cell transfer and sacrificed 4 days thereafter. All animals were maintained in HEPA filtered air. Randomly selected microscopic fields of the lung (250/animal) were judged to be normal or abnormal without knowledge of treatment. There was a low level of pulmonary response to an IT challenge of M. faeni in media recipients. There was a substantial increase (P < .01) in pulmonary abnormalities in the animals receiving blasts from the 10-μg/mL M. faeni 2-week group. Addition of cells from incompetent cell populations (0 μg/mL M. faeni 2-week donors or 10 μg/mL M. faeni 8-week donors) did not alter the ability of competent populations to transfer EHP. Cells cultured with antigen had a decreased proportion of T cells and an increased proportion of SIg + and large cells. Competent and incompetent cell populations did not differ in regard to proportion of large cells, surface Ig+, or T cells. We conclude that the inability of certain cell populations to transfer EHP is not associated with the appearance of functional suppressor cells. Differences of ability to transfer EHP do not correlate with differences of size distribution or T and B cell composition.