Although the systemic and local immune response to the
O antigen of Escherichia coli has been well characterized, little information is available on the immune response to K anigen. Experimental hematogenous
pyelonephritis was produced with Escherichia coli 06 K13 H1 and the serum and local (intrarenal) antibody response to O and
K antigens was determined with the
enzyme-linked
immunosorbent assay. Both local and serum antibody responses to the
K antigen were significantly less than that to the
O antigen. The
K antigen induced low titer
IgM and
IgG antibody responses in fewer than one-half of the animals and did not induce a local
IgA response in any animal. In contrast, the
O antigen induced local antibody responses in each of the
immunoglobulin classes in all animals from day 9 of
infection. Similarly, the serum
IgM and
IgG antibody titers to the
K antigen were significantly less than those evoked in response to the O component of the Escherichia coli. No serum
IgA anti-K
antibodies were detected. These observations helf clarify the roles of these two
antigens in
pyelonephritis. Although the
K antigen of Escherichia coli functions as a
virulence factor in upper
urinary tract infections, this
antigen does not elicit a significant immune response, whereas the
O antigen does induce a significant antibody response which could be of protective or diagnostic benefit.