HUMORAL AND CELLULAR IMMUNE RECOGNITION OF HELICOBACTER-PYLORI PROTEINS ARE NOT CONCORDANT

Helicobacter pylori is a major cause of chronic antral gastritis and p eptic ulcer disease. Further definition is needed of the factors that determine whether infected individuals remain asymptomatic, or ultimat ely develop ulceration of the mucosa or transformation to malignancy. To explore the possibility that host response to H. pylori may play a role in the outcome of this infection, we have examined humoral and ce llular recognition of several N. pylori proteins by seropositive and s eronegative persons. A complex mixture of water-extractable cell prote ins, which did not include lipopolysaccharide (LPS), was recognized by serum antibodies only in seropositive or infected individuals. IgG fr om seropositive subjects also bound to urease and to a heat shock prot ein (hsp)60 that is homologous to the 65-kD mycobacterial heat shock p rotein, while sera from uninfected individuals were negative. Although antibody responses to these antigens were restricted to seropositive subjects, T cell recognition of the same proteins was found in both se ropositive and seronegative subjects. The water extract of H. pylori s timulated peripheral blood mononuclear cells (PBMC) from all subjects, while purified proteins activated lymphocytes of only some seropositi ve and seronegative subjects. PBMC that were activated by the H. pylor i hsp60 did not respond to the autologous human p60 heat shock protein . These results demonstrate that, in contrast to antibody responses, T cell recognition of H. pylori proteins may occur in non-infected pers ons. In addition, the data suggest that in these subjects, peripheral lymphocytes that are activated by bacterial heat shock proteins do not mediate tissue damage by recognition of human heat shock homologues.