Circulating connective tissue components including the aminoterminal propeptides of
type III collagen (
PIIINP),
type I collagen (PINP) and
hyaluronan were determined in patients hospitalised for
pneumonia of suspected bacterial origin. Ninety patients were included, 64 of these were followed prospectively for up to 21 days after initiation of
therapy. Serum
PIIINP was determined by RIA, s-PINP by ELISA, and s-
hyaluronan by a radiometric assay. S-
PIIINP rose significantly above the zero value within 24 h in both
pneumococcal pneumonia (T0: 5.3 microg/l, 95% CI: 2.7-8.1 microg/l vs. T1: 6.7 microg/l, 95% CI: 3.8-9.1, P<0.01) and in
pneumonia of unknown aetiology (T0: 4.0 microg/l, 95% CI: 3.6-4.8 vs. T1: 4.5 microg/l, 95% CI: 3.8-5.1, P<0.05) followed by a gradual decline. At T1, S-
PIIINP was higher in
pneumococcal pneumonia compared with
pneumonia of unknown aetiology (P<0.05). By contrast, s-PINP tended to decline within 24 h in both
pneumococcal pneumonia (T1: 30 microg/l, 95% CI: 23-40, ns) and in
pneumonia of unknown aetiology (T1: 32 microg/l, 95%
CI: 22-42, ns) followed by a steady increase. The PINP
antigen size distribution remained constant throughout the follow-up period. S-
hyaluronan in
pneumococcal pneumonia paralleled s-
PIIINP reaching a peak value on day 1 (121 microg/l, 95% CI: 65-191, P=0.38). There was a positive correlation between s-
PIIINP and
C-reactive protein (CRP). The study demonstrates, that community-acquired
pneumonia elicits a differentiated mesenchymal response, which is turned down in response to successful
antibiotic therapy.