To demonstrate the roles of M and NK cells in cellular rejection of guinea pig cardiac xenografts.the ratswere randomly divided into 5 experimental groups: no treatment(A); CCV treatment (B); CCV

anti-Mditreatment (C)

CCV

anti-NK treatment(D)

and CCV

anti-Mth and anti-NK treatment (E). Rats were given i. p.of o.2 mgCCV; 250μg anti-MimAb and 250μg anti-NKmAb on day -3

-2

- 1 and day 0 relative to lieartgrafting. The graft survival time in each group was measured and the rejected hearts were studiedmicroscopically and inununohistochemically.The results showed rats receiving combination therapy using CCV

anti-MmAb and anti-NKmAb have significantly prolonged graft survival(38±12.5h in group E vs 0.25±0.12hin group A

P＜0.01

vs 18±10.2 h

16±8.6h

and 20.21±12.4h in groups B C and D respectively

P＜0.05).Histopatholgy and immunohistochemistry of the rejected hearts revealed typical lesions of hyperacute rejection with massiveC

deposition in groupA

interstitial heamorrhage

myocytolysis

and no C3 deposition in groups B

C

D

E

Compared with a large degree of monocyte infiltration in groups B

C

D

the monocyte infilatration in group E wasreduced significantly. It is concluded that both CCV therapy and combination therapy using CCV

anti-MdimAb

anti-NKmAb can enable transplanted guinea pig hearts to survive longer

therefore indicating that macrophageand natural killer cells play important mediating roles in xenograft cellular rejection.