Human T-cell immunity against Bordetella pertussis analyzed at clonal level

Cloned peripheral blood T lymphocytes from an immune donor were grown in interleukin 2 and tested for proliferation in response to inactivated Bordetella species (B. pertussis, B. parapertussis and B. bronchiseptica) and mutants deficient for the expression of virulence-associated antigens. All the T-cell clones obtained were CD4+8- and recognized specifically the Bordetella antigens when presented by autologous B cells. On the basis of the responsiveness to the whole inactivated bacteria, it was possible to cluster the twelve clones obtained into four groups with the following specificity: 1) filamentous hemagglutinin (FHA): 2) B. pertussis specific antigens; 3) virulence-associated Bordetella specific antigens; 4) non-virulence-associated Bordetella specific antigens. Employing two new B. pertussis deletion mutants, clone 6 (representative of cluster 1), was found to recognize the C-terminus of FHA. Furthermore, 3 out of 4 clones of cluster 3 were specifically stimulated by the soluble 69,000 MW protein from the outer membrane of B. pertussis. Surprisingly, none of the twelve clones obtained by stimulation in vitro with whole inactivated bacteria recognized PT. Thus, PT does not seem to be the most representative antigen on the whole inactivated bacteria. However, when a new generation of clones was obtained using soluble PT as the in vitro stimulus, it was observed that 11 clones of this group recognized this antigen. Furthermore, the majority of them was against the subunit S1 of PT. Therefore, we can conclude that a T-cell memory against PT exists in a donor who has had pertussis several years before. In conclusion, these results provide useful information in the attempt to obtain a simplified acellular vaccine for whooping cough.