Histology of liver allografts is the gold standard for diagnosis of ac
ute cellular rejection. However, scoring the severity of rejection and
distinguishing it from other infiltrations is not easy, Only one grou
p has evaluated biopsies morphometrically and also suggested that eosi
nophils are a specific diagnostic feature. We quantitated eosinophil c
ount in 92 biopsies in a group of 25 patients and, in another group of
30 patients, used morphometric image analysis to measure the cross-se
ctional area and cell density in each portal tract in day 5 protocol l
iver biopsies. Rejection was diagnosed by pathological evaluation conf
irmed with clinical and biochemical graft dysfunction graded histologi
cally into mild or moderate-to-severe. The control groups were five pa
tients with no rejection, nine patients with CMV infection, and eight
biopsies in eight patients for whom the cause of the liver dysfunction
was obscure. The cross-sectional area, the inflammatory cell count of
each portal tract and the mean portal tract inflammatory cell density
(cells/mm(2)) increased with the severity of rejection. In each case
the regression coefficient was statistically significant. Correlating
the mean of the total inflammatory cell count with the mean of the por
tal inflammatory cell density (cell/mm(2)) gave far better separation
of the mild rejection and moderate-to-severe rejection groups. Eosinop
hils were specific for the presence of acute cellular rejection and in
creased with the severity of rejection. They were absent in the no rej
ection group, in the CMV group and in those with obscure liver dysfunc
tion. The eosinophil count fell markedly following treatment of reject
ion. We conclude that morphometric image analysis can be used to quant
ify acute cellular rejection and that eosinophils are a specific featu
re of acute cellular rejection.