Which are both intrinsic cell wall constituents and secretory molecules some

Microarray analyses showed exclusive IgG mAb binding to b1,3-linked glucose sequences with DP 4 and greater. In contrast, the IgM mAb bound both to b1,3- as well as to b1,6-linked glucose sequences with DP 2 and greater. As shown by microarray analyses it also recognized saccharides with b1,4 glucan sequences, which are ordinarily absent in fungi but present in higher plants and lichens. Interestingly, a linear b1,3-b1,4-linked glucan is uniquely present in the cell wall of Aspergillus fumigatus, a fungus which is bound by both mAbs, as found by immunofluorescence staining, and whose growth is highly susceptible to the anti-b-glucan antibodies generated by the immunization with the Lam-CRM vaccine. The disposition of b1,3 glucan on C. albicans cell surface, an essential Mepiroxol prerequisite for interaction with the protective anti-bglucan mAb, is a matter of controversy. There are suggestions that b1,3 glucan is hidden inside the cell wall by a layer of mannoprotein constituents and that it is lacking or negligibly Danshensu expressed on the fungal surface, particularly in hyphal cells. This sort of b-glucan stealth has been recently interpreted as a host-deceiving mechanism, as it would prevent the binding of fungal cells by Dectin-1 – a b1,3 glucan specific receptor present on a variety of cells of the innate immune system – thus inhibiting the triggering of critical signals for coupling innate to adaptive antifungal immunity. However, other authors have reported surface expression of this polysaccharide in both yeasts and hyphae. This apparent discrepancy could be reconciled by very recent reports that b1,3 glucan may be variably expressed by fungal cells depending on their growth conditions and/or morphology. Moreover, different reagents, with likely different fine specificity, were used by the various Authors to detect b1,3 glucan at cell surface. The IF and EM data shown here with the use of a mAb with restricted specificity for b1,3 glucan leave little doubt that some b1,3 glucan or components carrying this polysaccharide are expressed on cell surface, albeit not in all cells of the culture and not uniformly in all labelled cells. This would be expected in a asynchronous culture if b1,3 glucan is consistently exposed only at certain stages of growth. Interpretation of all these data must take also into account the presence of b1,3 and b1,6 glucan moieties in the mannoprotein modules of the cell wall.