The primary hypothesis is that the costimulatory B7 glycoprotein abnormalities identified in the murine MKD model will be recapitulated in sera obtained from human HIDS patients, either before, during or after febrile episodes. The secondary hypothesis is that B7 glycoprotein molecule levels will correlate with clinical symptomatic severity score, other known biomarkers of HIDS, markers of inflammation and or markers of isoprenoid metabolism.