Characterisation of the Ocular Surface Leukocyte Populations before and after Haemopoietic Stem Cell Transplant in Patients with and without Ocular Disease.

Abstract

 

Purpose

 

Ocular complications of haemopoietic stem cell transplant (HSCT), such as dry eye and cicatrizing conjunctivitis, are common, particularly in the context of graft-versus-host disease. Our aim was to characterize the conjunctival leukocyte populations before and after HSCT in patients with and without ocular disease.

 

Methods

 

23 patients, 100 days post-HSCT and six healthy controls were recruited. Additionally, six patients were recruited and seen before HSCT and at 1, 3, 6 and 12 months post-HSCT, with one patient unfortunately succumbing to disease recurrence. None of the longitudinal patients developed ocular disease. As part of the HSCT protocol, all patients had T-Cell depletion with Alemtuzumab pre-transplant. At each visit, Schirmer’s test and conjunctival impression cytology were performed. Cells were stained with fluorochrome-labeled antibodies and analysed by flow cytometry to phenotype leukocyte populations.

 

Results

 

In the longitudinal cohort, conjunctival CD4 and CD8 lymphocytes numbers dropped following HSCT, remaining lower than pre-HSCT at 3 months. At 6 months, the CD8 population had returned to normal, but the CD4 population were elevated compared to pre-HSCT and healthy volunteers. These changes reflected the lymphocyte levels in the blood, where at 3 months there were lower levels of both CD4 and CD8 lymphocytes. Interestingly, in the 100 day post-HSCT cohort, the conjunctiva of patients with dry eyes (9/46 eyes of five patients with a Schirmer’s of 5mm or less) contained a significant elevation of both neutrophils (p=0.002) and monocytes (p=0.001) as compared to those eyes with a normal Schirmer’s test.

 

Conclusions

 

We have demonstrated that, following HSCT, the resident CD8+ conjunctival lymphocyte populations declined rapidly, with reconstitution taking up to 6 months. The elevation in CD4 lymphocytes at later time points may indicate abnormal conjunctival immune reconstitution, which may predispose the ocular surface to inflammation. In patients with dry eye there was evidence of ocular surface inflammation, as demonstrated by raised numbers of neutrophils and monocytes, justifying the use of anti-inflammatory treatment.

 

 

Median Conjunctival CD4 Cells in Healthy Volunteers; before HSCT, and at 1,3,6, and 12 months after stem cell transplantation.

 

 

Conjunctival Leukocytes in dry& normal eyes post-stem cell transplant.

 

Keywords: 474 conjunctiva • 529 flow cytometry • 557 inflammation