An Outbreak of Hepatitis A among Cancer Patients Treated with Interleukin-2 and Lymphokine-Activated Killer Cells

An outbreak of hepatitis A virus (HAV) infection occurred among cancer patients treated with interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells between July and September 1986 at six different clinical centers. Among 85 patients tested serologically for recent HAV infection, 22 (39%) of 56 susceptible patients developed acute HAV infection. Only exposure to LAK cells cultured in medium containing human serum from two specific manufactured pools was associated with HAV infection. Attack rates were 85% among patients exposed to pool X, 62% in patients exposed to pool Y, and 50% in those exposed to both pools, compared with none among the 24 susceptible persons exposed to other serum pools (P less than .001). The serum used in production of LAK cell medium was obtained from multiple paid donors. Twenty persons donated plasma to both serum pools X and Y. Although none of 12 donors tested had evidence of recent HAV infection, it is likely that an asymptomatic plasma donor viremic for HAV contaminated both serum pools and the LAK cell medium made from it.