Studies on experimental pulmonary granulomas. I. Detection of lymphokines in granulomatous lesions.

Granulomatous reactions were immunologically induced in guinea pigs by several procedures, including intravenous injections of Bacille Calmette Gúerin (BCG) into animals immunized with complete Freund's Adjuvant and an intravenous injection of agarose beads linked to a specific antigen (dinitrophenylated bovine serum albumin) into immune animals. The tissue extracts obtained from lungs at various stages of granuloma formation were examined for macrophage migration inhibition (MIF) activity. The activity was found in a high incidence during the early stages of the granulomatous response. In contrast, MIF activity could be detected only rarely in granulomatous spleens and not in granulomatous livers. Chemotactic factor activity and mitogenic factor activity were only sporadically detectable. The MIF activity was associated with fractions showing chemical heterogeneity. One fraction was physicochemically indistinguishable from conventional lymphocyte-derived MIF; the other was a substance of large molecular weight. These results demonstrate the presence of biologically active mediators in immune granulomas, which may be related to early events involved in the induction or enhancement of such reactions.