PASSAGE OF LEUCOCYTES THROUGH THE ENDOTHELIUM OF ARTERIES

IAN C m * AND A. IVANOV School of Pathology, University of New South Wales, and Department of Pathology, Prince Henry Hospital, Syalney

PLATE CIX

IN inflammation leucocytes migrate through the walls of venules, and to a lesser extent through capillaries (Cohnheim, 1889). They are held up, just outside the endothelium (Zweifach, 1955) by basement membrane (Marchesi and Florey, 1960). “ Not a single colourless or red corpuscle ever extravasates from the arteries ” (Cohnheim, p. 259), except in arteritis. This note reports the migration of neutrophil poly- morphonuclear leucocytes through arterial walls, as seen by chance in a surgical resection specimen.

CASE REPORT

A 39-yr-old woman with normal blood pressure was admitted to hospital because of acute intestinal obstruction. At operation several feet of the distal part of the small intestine were found to be gangrenous. No mechanical cause of obstruction was noted. The gangrenous small intestine, the caecum and the ascending colon were resected. The patient’s blood pressure remained low after the operation, her urine output fell and she died in uraemia three days after operation.

The surgical specimen comprised 180 cm. of small intestine, caecum and colon. The small intestine was gangrenous from a point 20 cm. from the proximal line of resection.

The significant histological changes were present in the mesenteric blood vessels.. The veins contained recent adherent thrombus. Only a few arteries contained thrombus; in many of the rest neutrophil polymorphs lay peripherally against the wall of the vessel, and were present in large numbers between the endothelium and the internal elastic lamina. In some arteries they were evenly distributed all round the wall, whilst in others they were aggregated, giving a festooned appearance (figs. 1-4). In a few cases, polymorphs had penetrated the elastic lamina into the muscular coat of the artery, and rarely right through the wall. There was no evidence of necrosis of the arterial walls.

Present address: Department of Human Biology and Anatomy, University of Sheffield.

I. PATH. BACT.-VOL. 90 (1965) 401

408 JAN CARR A N D A . JVANOV

COMMENT The most likely order of events here was thrombosis of the mesen-

teric veins, possibly due to twisting of the intestine, followed by stasis, and acute passive congestion of the arteries.

The usual reason given for the failure of leucocytes to migrate through arterial walls is the simple one that flow is too fast to allow the leucocytes to settle out at the periphery of the vessel (Cohnheim, p. 250). This fits in with the demonstration here that when flow is slowed migration occurs. Marchesi and Florey (1960) stated that a significant barrier to the passage of leucocytes through the walls of small veins is the basement-membrane. This is borne out by the demon- stration here that when leucocytes do migrate through the endothelium of arteries, they are held up by a mechanical barrier, in this case the fenestrated elastic membrane. This barrier is efficient, but not complete.

SUMMARY Polymorphonuclear leucocytes have been observed to migrate

through arterial endothelium, but to be largely held up by the internal elastic lamina, in circumstances where there was reason to suppose that arterial flow was slowed. This is held to confirm some current concepts on the more usual migration of leucocytes through the walls of capillaries and veins.

REFERENCES COHNHEIM, J. . . . . . . . 1889. Lectures on general pathology,

MARCHES, V. T., AND FLOREY, H. W. 1960. ZWEIFACH, B. W. . . . . . . 1955. Ann. N . Y . Acad. Sci., 61,670.

London, vol. I . Quart. J . Exp. Physiol., 45, 343.

Addendum A similar lesion has recently been described by Crompton (1964), and is

interpreted by him as a manifestation of vascular stasis.

CROMPTON, M. R. REFERENCE . 1964. Brain, 87, 49 I .

CARR AND IVANOV PLATE CIX

ARTERIAL ENDOTHELIAL PASSAGE OF LEUCOCYTES

FIG. 1.-Two thrombosed veins and FIG. 2.-Longitudinal section of artery, small artery showing subendothelial showing subendothelial polymorphs. polymorphs. Haematoxylin and eosin. HE. x 180. x 70.

FIG. 3.-Cross-section of artery showing subendothelial polymorphs, a few of which have penetrated the elastica. HE. x180.

FIG. 4.-Cross-section of artery showing subendothelial polymorphs internal to the internal elastic lamina. HE. ~ 4 8 0 .