Production of TNF-alpha, IL-1beta, IL-12 and IFN-gamma in murine peritoneal macrophages on treatment with wheat germ agglutinin in vitro: involvement of tyrosine kinase pathways.

Treatment of macrophages with various doses of wheat germ agglutinin (WGA) for different time intervals resulted in enhanced expression of TNF-alpha, IL-1beta, IL-12 and IFN-gamma. The maximum expressions were observed at 24 h with 100 ng/ml of WGA. Enhanced transcription of cytokines TNF-alpha, IL-1beta, IL-12, and IFN-gamma was observed at 16 h of WGA treatment by RT-PCR. Pharmacological inhibitor of tyrosine kinase, PI3 kinase, protein kinase C, p42/44, p38, JNK and intracellular calcium immobilizing agent down regulated the WGA induced expression of cytokines TNF-alpha, IL-1beta, IL-12 and IFN-gamma. Maximum protein tyrosine kinase activity in macrophages was seen at 5 min of WGA treatment. Maximum cytosolic Ca++ was observed at 10 min of WGA treatment. WGA treated macrophages showed maximum activation of protein kinase C (PKC) and PI3 kinase at 10 min, p42/44, p38 at 15 min and JNK at 30 min. Transcription factor ELK1 was activated at 60 min and IêB, c-Fos and c-Jun at 30 min of WGA treatment. The pharmacological inhibitors were also used to check the cascade of activation of tyrosine kinase, PKC, PI3 kinase, p42/44, p38, JNK and release of calcium from intracellular storage to sort out the signal pathways involved in the release of TNF-alpha, IL-1beta, IL-12, and IFN-gamma by macrophages on treatment with WGA in vitro.