Dr. Askenase discovered a series of steps from challenge with antigen, in a sensitized host, to the entry of T cells into the site of challenge. This work on allergy uncovered a previously unrecognized role of: B-1 B cells, NKT cells, IL-4, complement, serotonin and mast cells. These findings are relevant to the diagnosis and therapy of allergic and autoimmune diseases, as well as cancers and transplantation. These studies led to questions of the value of allergic responses and thus to experiments of immune responses to ectoparasite ticks and showed that allergy cells; particularly basophils, are required for immune rejection of these ectoparasite hosts; an evolutionary explanation for allergy responses. Currently, his laboratory is performing novel new studies on immune regulation by exosomes, delivering miRNA to other cells, that are made by every cell and conserved through evolution and thus made in some form by all species down to bacteria.