Binds human IgE in vitro, and may neutralize IgE antibodies present in blood from repeatedly tick-bitten people. Does not have antimicrobial activity against E.coli or M.luteus. Expressed in gut and hemolymph. Not expressed in salivary glands, ovarium or Malpighian tubes. Expressed in response to bloodmeal throughout all developmental stages including larva, nymph and adult. Slightly expressed in unfed ticks. The expression starts to increase on the first day of feeding and reaches the maximum on the third day. The level remains stable until full engorgement. By bloodmeal. Belongs to the NPC2 family.