FIG. 2.

Immunohistochemical analysis of the effects of TNF neutralization on the B-cell aggregates-macrophage units in the lungs of C57BL/6 mice persistently infected with M. tuberculosis. Lungs were obtained from mice at 6 months postinfection prior to the administration of MP6-XT22, and subsequently at 9 days (9d) and 21 days (21d) posttreatment (Tx), optimal cutting temperature embedded, cryosectioned, and stained for macrophages (F4/80⁺) to identify the B-cell aggregate-macrophage subunit. Control mice received rat IgG treatment. Virtually all lymphoid aggregates in the lungs of mice with chronic tuberculosis are B-cell nodules (38). “B” denotes aggregates of B lymphocytes; macrophages are designated by “M.” Total magnification, ×100. Samples are representative of sections from three or four mice per treatment group per time point (three sections per mouse). The study was repeated once with similar results.