Kinetic study of mast-cell growth factor production by lymphocytes during the course of Strongyloides ratti infection in mice.

Mast-cell growth factor (MCGF) activity in the media conditioned by mesenteric lymph node or spleen cells from Strongyloides ratti-infected C57BL/6 mice was examined by using factor-dependent cell line FDC-P2 or bone marrow-derived, cultured mast cells (BMMC) as indicators. Mesenteric lymph node cells from infected mice spontaneously released MCGF activity by culturing for 24 h, showing peak production on days 5-7. MCGF production by mesenteric lymph node cells was augmented after stimulation with adult worm antigen or with concanavalin A (con A). The peak of MCGF production by antigen-stimulated lymph node cells was observed on days 5-7 and declined thereafter. MCGF production by antigen-stimulated spleen cells was lower than that by lymph node cells and reached a peak on day 7 or later. Normal lymph node or spleen cells did not produce MCGF activity even after stimulation with adult worm antigen. The peak of MCGF production by mesenteric lymph node cells preceded the peak of intestinal mastocytosis at the infected site by 4-6 days. The cells producing MCGF had a phenotype of Thy-1+, L3T4+, and Lyt-2-. The possible importance of mucosal mast cells in worm expulsion is discussed.