Cellular immunity in adolescents and adults following acellular pertussis vaccine administration

Abstract

Cell-mediated immune (CMI) responses to an acellular pertussis vaccine administered to 49 subjects, a subset of participants in the National Institutes of Health-funded adult acellular pertussis vaccine efficacy trial, were evaluated and compared with antibody responses to vaccine antigens. Levels of proliferation of and cytokine secretion from lymphocytes cultured in the presence of pertussis toxin, filamentous hemagglutinin, or pertactin were measured before vaccination and 1 month and 1 year after vaccination. Statistically significant increases in lymphocyte stimulation indices and cytokine secretion were noted at both 1 month and 1 year after vaccination. Brisk pertussis antigen-specific immunoglobulin G responses were also noted at 1 month after vaccination, but these responses had declined by nearly 50% at 1 year after vaccination. These studies clearly demonstrate that both cellular and humoral immune responses occur after the administration of acellular pertussis vaccines to adolescents and adults but that the CMI responses are of greater magnitude and longer duration. CMI responses may be a better correlate of long-term protection.

FIG. 1.

Responses of subjects to an acellular pertussis vaccine. The proliferation of pertussis antigen-specific lymphocytes (a and c) and antibody concentrations (b and d) were measured. Lymphocytes from 49 vaccinated subjects (aP group) (a) and those from the 6 members of the control group (c) were cultured in the presence of antigens (10 μg/ml PT, 10 μg/ml FHA, or 10 μg/ml PRN). [³H]thymidine (0.5 μCi) was added during the last 16 h of culture, and the level of incorporation was measured by scintillation counting (counts per minute). Stimulation indices were calculated as follows: (counts per minute for the culture with the antigen)/(counts per minute for the medium control). Serum samples from the vaccinated subjects (b) and the control group (d) were analyzed for pertussis antigen-specific IgG with ELISA. IgG concentrations are expressed as EU/ml. Lymphoproliferation measurements and serum antibody concentrations increased significantly at 1 month (post 1 m) and 1 year (post 1 yr) postvaccination compared to corresponding prevaccination (pre) values. Shaded bars indicate interquartile ranges, and black horizontal lines indicate median values. The outlier value (*) is attributed to a single subject; although the value for pertussis antigen-specific lymphoproliferation is high, prevaccination versus postvaccination data for the outlier did not reflect an impact of the vaccination.