Immunologic Response to Pneumococcal Polysaccharide Vaccine in Splenic Injury Patients

The study is a multi-institutional, prospective trial, conducted primarily at the University
of California, Davis Medical Center (UCDMC) by the Department of Surgery, Division of Trauma
and Acute Care Surgery. The angioembolization arm will be multicenter while the nonoperative
group will be enrolled only at UCDMC. There will be a total of 90 subjects, with 30 in each
of the three arms (nonoperative, angioembolization, splenectomy).

Adult trauma patients (defined as those aged 18 to 65 years old) sustaining a splenic injury
and planned nonoperative management, are eligible for enrollment in the nonoperative arm. The
management decision for the splenic injury is entirely at the discretion of the attending
trauma surgeon. Any patient who subsequently undergoes embolization or splenectomy will be
withdrawn from the study.

Adult trauma patients sustaining a splenic injury and undergoing splenic artery embolization
are eligible for enrollment in this arm of the study. The management decision for the splenic
injury is entirely at the discretion of the attending trauma surgeon and radiologist. All
patients undergoing successful splenic artery embolization (no subsequent splenectomy or
splenorrhaphy, i.e., no cross-over) are eligible.

Patients managed nonoperatively will be vaccinated within three days of their diagnosis, per
standard operating protocol at UCDMC. At the time of vaccination, 7cc of venous blood will be
collected for baseline antibody analysis. Patients will return four weeks later for a
follow-up phlebotomy of another 7cc of blood for analysis of functional antipneumococcal
antibody generated in response to vaccine antigen challenge. Blood samples will be
centrifuged and stored, and stored sera will be sent in batches on dry ice to Flow
Applications, Inc. in McDonough, Georgia for antibody analysis. All samples will be assigned
unique patient identifiers.

Responses to the 23-valent pneumococcal polysaccharide vaccine will be measured by ELISA to
determine the geometric mean increase in immunoglobulin G (IgG) antibody titer to
pneumococcal polysaccharide (Pnc Ps) serotypes. Functional antibody, measured by percent kill
of a known pneumococcal concentration, will be determined by opsonophagocytosis assay (OPA).
Titers for serogroup 4 and serotypes 6B, 19F, and 23F will be measured, and geometric mean
rises in antibody concentrations will be determined to measure response to vaccination.

For those treated with nonoperative management, degree of antibody response and grade of
splenic injury will be analyzed against normal controls.

Patients treated via splenic artery embolization will undergo a standard post-embolization
computed tomographic exam of the abdomen three to five days postinjury to evaluate the
effectiveness of the embolization procedure. The percent of viable, perfused spleen will be
calculated from this CT. Antibody response will be compared against the location of the
intravascular coils (i.e., proximal versus distal embolization) and the percent of viable
spleen as calculated on the follow-up CT scan.

Inclusion Criteria:

- Adult trauma patients (aged 18 to 65 years old) sustaining a splenic injury.

Exclusion Criteria:

- Ages less than 18 and greater than 65

- Initial planned nonoperative management patient who subsequently undergoes
embolization or splenectomy will be withdrawn from the study.