Effects on immunity of multiple leukapheresis using a rapidly excreted analog of hydroxyethyl starch

Immunologic studies were performed immediately before and after leukapheresis in five subjects undergoing four granulocyte donations (separated by 3- to 4-week intervals) using continuous-flow centrifugation leukapheresis with a rapidly excreted investigational analog of hydroxyethyl starch. Postleukapheresis donor blood lymphocyte counts and serum immunoglobulin levels decreased transiently, but significantly, during each procedure when compared with preleukapheresis values due simply to plasma volume expansion (acute effects of dilution). Possible long-term effects of repeated procedures were investigated by comparing preleukapheresis values before the first and fourth procedures. Total lymphocyte, total T-lymphocyte, and T4-lymphocyte counts, as well as serum immunoglobulin values and anti-A and B titers measured before the fourth procedure remained unchanged when compared with values obtained before beginning the series of procedures. In contrast, the B-lymphocyte count was decreased, the T8-lymphocyte count was increased, and the T4:T8 ratio was decreased due to the increase in the T8-lymphocyte count. Although statistically significant (p less than 0.05), all changes were slight, and clinically significant effects on donor humoral immunity could not be detected. The mechanisms involved, however, may be of biologic and therapeutic interest.