Defense against chitin containing fungal pathogens (Probable). Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Causes an allergic reaction in human. Binds to IgE of patients allergic to both the Indian jujube and latex (PubMed:16122801, PubMed:18435802, PubMed:22289730). Natural protein binds to IgE of patients allergic to the fruit of the Indian jujube. Recombinant protein binds to IgE in 87.5% of the 8 latex- and Indian jujube-allergic patients tested (PubMed:16122801). May stimulate allergic inflammation by inducing T-helper type 2 (Th2)-specific immune responses including increased production of cytokines, most predominantly IL13, from peripheral blood mononuclear cells (PBMC) of patients allergic to both latex and the fruit of the Indian jujube. Chitinase activity is required for this function (PubMed:22289730). Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily.