Mediators of intercellular communication in immune responses

The immune system is in charge of clearing the human body of pathogens and tumor cells to prevent, resolve or mitigate disease. To fulfill this task it employs many different cell types with unique capabilities, as each threat requires a different strategy to ensure clearance. Intercellular communication is of vital importance to activate or inhibit the appropriate (immune) cells at the right moment. Cells can communicate with each other through direct cell-cell contact or remotely through secretion of soluble signaling molecules. These soluble molecules include secreted proteins that can be recognized by other cells if they express the right receptors. We developed a library of human secreted proteins for use in several high-throughput screens to identify additional secreted proteins that affect specific immune responses. This approach led to the identification of fibroblast growth factors as a class of viral replication inhibitors, soluble FAS ligand as an inducer of memory B cell differentiation into antibody secreting cells, and IL-21 an inducer of granzyme B expression in activated CD4+ T cells. In addition, the research in this thesis describes that tumor infiltrating lymphocytes (TILs) derived from renal cell carcinoma cannot make sufficient cytokines when co-cultured with autologous tumor digest, a type of secreted proteins, after in vitro expansion. In conclusion, this thesis revealed additional roles of known secreted proteins that support intercellular communication during immune responses, thereby expanding our knowledge of immunological communication

Agricultural extension messages using video on portable devices increase knowledge about seed selection, storage and handling among smallholder potato farmers in southwestern Uganda

Open Access JournalTo feed a growing population, agricultural productivity needs to increase dramatically. Agricultural extension information, with its public, non-rival nature, is generally undersupplied, and public provision remains challenging. In this study, simple agricultural extension video messages, delivered through Android tablets, were tested in the field to determine if they increased farmers’ knowledge of recommended practices on (i) potato seed selection and (ii) seed storage and handling among a sample of potato farmers in southwestern Uganda. Using a field experiment with ex ante matching in a factorial design, it was established that showing agricultural extension videos significantly increased farmers’ knowledge. However, results suggested impact pathways that went beyond simply replicating what was shown in the video. Video messages may have triggered a process of abstraction, whereby farmers applied insights gained in one context to a different context