IMMUNE-RESPONSES OF SPLENECTOMIZED TRAUMA PATIENTS TO THE 23-VALENT PNEUMOCOCCAL POLYSACCHARIDE VACCINE AT 1 VERSUS 7 VERSUS 14 DAYS AFTER SPLENECTOMY

Objectives: Pneumcoccal polysaccharide vaccine is given after emergenc y splenectomy for trauma to lessen the risk of overwhelming postsplene ctomy sepsis. This study was undertaken to determine optimal timing of vaccine administration as determined by serum type-specific polysacch aride antibody concentration titer and functional activity of the resu lting antibodies. Methods: Fifty-nine consecutive patients undergoing splenectomy after trauma mere randomized to receive pneumococcal vacci ne postoperatively at 1, 7, or 14 days. Immunoglobulin G serum antibod y concentrations against serogroup 4 and serotypes 6B, 19F, and 23F me re measured before vaccination and 4 weeks postvaccination. Antibody c oncentrations were determined by enzyme-linked immunosorbent assay, an d functional antibody by opsonophagocytosis. Results were compared wit h a normal adult control group (n = 12). Results: Postvaccination enzy me-linked immunosorbent assay immunoglobulin G antibody concentrations for all serogroups and serotypes studied mere not significantly diffe rent in splenectomized patients and control subjects. Postvaccination functional antibody activity was significantly reduced in early vaccin ation groups (serotype 6B excepted). However, with the exception of 19 F, all titers for the 14-day group approached those of the control sub jects (p > 0.05). Fold-increases of opsonophagocytic titers for serogr oup 4 and serotypes 6B and 19F showed progressive increases with delay in vaccination. Except for serotype 23F, the number of postsplenectom y patients with opsonophagocytic titers < 64 significantly decreased w ith a delay in vaccination (14 days). Conclusions: Postvaccination imm unoglobulin G serum antibody concentrations were not significantly dif ferent from normal control subjects regardless of the time of vaccinat ion (1, 7, or 14 days). Although concentrations approach normal, funct ional antibody activity was significantly lower. Better functional ant ibody responses against the serogroup and serotypes studied seemed to occur with delayed (14-day) vaccination.