Abstract
Pulmonary granulomas (GR) with type 1 or type 2 cytokine involvement were induced in presensitized CBA mice by embolization of beads coupled to purified protein derivative (PPD) of Mycobacterium tuberculosis or soluble Ags derived from Schistosoma mansoni eggs (SEA). Using neutralizing Abs against IFN-gamma, IL-10, and TNF-alpha/beta, we examined effects on GR size, GR macrophage function, and regional lymph node (LN) responses. Profoundly different effects were observed in the two models. Anti-IFN decreased PPD-GR size by 20%, but augmented SEA GR by nearly 50%. Anti-TNF abrogated PPD-GR area by 40% and SEA GR by 15% suggesting that TNF contributed more to the former. Anti-IL-10 did not affect GR sizes. Analysis of TNF indicated that IFN was required for maximum production by both PPD GR and SEA GR macrophages. Interestingly, TNF tempered its own expression by SEA GR macrophages. In LN, PPD GR and SEA GR formation was associated with T cell-dependent type 1 (IFN and IL-2) and type 2 (IL-10 and IL-4) cytokine profiles, respectively. In PPD LN, anti-IFN decreased IFN and IL-2 production by 50%. In contrast, anti-IL-10 increased IFN and IL-2 production by two- to fourfold, indicating that IFN and IL-10 had opposing effects on the type 1 response. In SEA LN, anti-IFN decreased IFN production but augmented IL-4 and IL-10 production by 50 and 90%, respectively, supporting the notion that IFN constrains Th2 responses. Conversely, IL-10 promoted the Th2 response. Surprisingly, anti-TNF reduced IL-4 and IL-10 in SEA LN but did not affect PPD LN, suggesting that TNF-alpha or -beta supports Th2 differentiation in LN during the secondary response to schistosomal Ags.
