C4d deposition is associated with immune cells infiltrating in kidney allograft glomerulitis and peritubular capillaritis.

OBJECTIVE

The aim of our study was to determine the amount and composition of immune cells within glomeruli and PTCs and its relationship with C4d deposition.

MATERIALS AND METHODS

Immunohistochemistry staining for C4d, CD3, CD68, granzyme B and Foxp3 was used for phenotyping and enumerating immune cells within intracapillaries.

RESULTS

C4d staining was present in 26 biopsy specimens (C4d(+)) and negative in 25 specimens (C4d(-)). The total number of infiltrating cells in glomerulus and PTC in C4d(+) was significantly higher than in C4d(-). Although the C4d(+) showed a significantly higher mean number of macrophages per glomerulus and PTC than in C4d(-) group, the C4d(-) showed a higher mean number of T cells per glomerulus and PTC than in C4d(+). Comparing cell counts in diffuse C4d(+) and focal C4d(+) groups, a significant difference of absolute numbers of intracapillary cells could be observed in glomeruli and PTCs. The mean number of macrophages per glomerulus and PTC in diffuse C4d(+) was greater than that of the focal C4d(+), while mean T cells per glomerulus and PTC were less in cases of diffuse C4d(+) than in focal C4d(+). The differences, however, did not achieve statistical significance. Not only glomerular T cells but also PTCs are granzyme B positive T cells totally.

CONCLUSION

The total number of infiltrating cells in glomeruli and PTC has association with PTC C4d deposition; the infiltrating cells were predominantly macrophages in C4d(+), especially in diffuse C4d(+), whereas the infiltrating cells were predominantly T cells in C4d(-). Glomerular and PTC T cells were cytotoxic phenotype completely.