Hepatitis B Vaccine

In an early study to assess patterns of immunogenicity response to vaccines in serum as compared to the MIMIC® System, we chose to test the correlation of response by serum and MIMIC® derived antibodies using Hepatitis B vaccine responses. Note that antigen specific memory cells are of low frequency in the periphery whereas secreted antibodies may be abundant. In this study, we selected twenty one (21) of our donors at random (i.e., independent of Hepatitis B immune status) and asked the question, "How do serological responses correlate with those elicited in the MIMIC® System?" Serological responses were enumerated by an immunosorbent assay (ELISA), which measures soluble antibodies in serum. MIMIC® responses were measured using an ELIspot assay, which is based upon cellular secretion of antibodies. This assay detects the presence antigen-specific B cells by reporting a spot on a plate. The results were normalized by counting the number of spots in each culture condition that received the vaccine against the number of spots in parallel LTE cocultures that were left unstimulated (i.e., received no vaccine). The true frequency of B cells in each condition was determined by flow cytometry.

We stratified the donor population into three (3) categories: high responders - individuals expressing serum titers greater than 1:2000, the maximum of the assay; mid-range responders - individuals who had significant but not maximal titers; and low responders - individuals whose titers were indicative of a naïve or non-responsive state. The results are presented below. Antibody titers from the serum of each donor (left) and ELIspot results with the MIMIC® System (right) show identical stratification into high, mid, and low responders. There is excellent correlation between serology and MIMIC® System results.