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The ability of polymorphonuclear leucocytes (PMNs) from elderly healthy subjects and post-operative cancer patients to ingest and kill Clostridium difficile was studied. The percentage of phagocytosis in clinically healthy subjects aged 69-82 years ranged from 20.2 +/- 3.2 (mean +/- SD) to 34.1 +/- 4.2, depending on the strain of C. difficile, from 6.7 +/- 2.2 to 11.2 +/- 2.2 in post-operative cancer patients aged 65-69, and from 68.4 +/- 3.1 to 81.1 +/- 6.3 in young healthy control subjects. In both study groups, the defect was in part serum-associated. Although the total number of bacteria killed by the PMNs was reduced in the two study groups, the percentage of ingested bacteria killed by the PMNs was similar to that in the young healthy subjects. These differences were not noted when Escherichia coli and Staphylococcus aureus were used as the test organisms. The defective PMN function against C. difficile in the elderly and post-operative cancer patients described in this study may offer an explanation as to why these individuals are at high risk of developing antibiotic-associated colitis.

Host defense mechanisms in transfusion-dependent non-splenectomized patients with beta-thalassemia were studied. Polymorphonuclear leukocytes (PMNLs) of non-splenectomized patients responded poorly to zymosan generated chemotactic factors. Chemotactic indices were 22.1 microns +/- 2.8 (mean +/- S.D.) using zymosan activated serum (ZAS) as the attractant in comparison to 20.4 microns +/- 2.6 when fresh untreated serum was used. In contrast, chemotactic indices of normal PMNLs increased from 21.1 microns to 33.6 microns +/- 3.1 in response to ZAS. Normal PMNL responses to a mixture of normal ZAS and thalassemic serum were inhibited; the mean chemotactic index was 18.1 microns +/- 5.1 with use of ZAS alone. Splenectomy temporarily reverses these alterations. Adherence to nylon wool of PMNLs suspended in fresh thalassemic serum prior to splenectomy was 3.1% +/- 1.1 (mean +/- S.D.); 20 days after splenectomy adherence increased to 14.0% +/- 2.8 (P = 0.0001) and remained at this level for 90 days. At 120 and 150 days after splenectomy adherence decreased to 1.5% +/- 0.8 and 1.0% +/- 0.85 respectively. Splenectomy also transiently abrogated the failure of zymosan to generate chemotactic factors in thalassemic serum.