dietary fiber [ 19 ]. It is possible that differences in the cultivation of mushrooms in different regions and by different growers may affect the composition of an important immunomodulatory factor. One of the limitations of the present study is that the results presented may only reflect results of mushrooms grown in Pennsylvania and more specifically by the manufacturers of those mushrooms in Pennsylvania. Future research should sample mushrooms from different suppliers of the same species for comparison of immunomodulatory functions. Several major substances have been isolated from mushrooms and shown to be immunomodulatory. What has not been considered is that mushrooms have a number of bacteria, yeasts and molds associated with them. In fact microorganisms are required for initiation of fruit body formation. Normal healthy mushrooms have high bacterial populations associated with them with the numbers ranging from 6.3 -- 7.2 log CFU/g of fresh mushrooms [ 19 ]. The bacteria associated with mushrooms are predominately the pseudomonads [ 19 - 22 ]. The pseudomonads have been shown to activate the innate immune response by interactions with the Toll like receptors (TLR), especially TLR-5 [ 23 - 25 ]. It is likely that the microbiota ingested with the mushrooms are triggering the mucosal innate immune response through the TLR. More research is required to determine the relative contributions of bacteria, versus nutrient and other components of mushrooms as immune system regulators. Conclusion Whole mushrooms have a number of components that are potentially immuno-modulatory. The in vitro data show that