CD 52 levels using flow cytometry.

 

Chronic Lymphocytic Leukaemia is the commonest from of leukaemia in the western world. The chronic leukaemia's are distinguished from acute leukaemia's by their slower progression and are more difficult to cure. CLL is a disease characterised by a clonal proliferation of B-lymphocytes in the blood, marrow and lymphoid tissues.

The leukaemic CLL B cell accumulation appears to be a result of defective apoptosis rather than uncontrolled proliferation.

As cures are rare in CLL, therapy often targets the symptoms of this disease rather than the disease itself. Chemotherapy in the disease can shorten life expectancy rather than prolong it if it is given to early.

Monoclonal antibody therapy is the use of monoclonal antibodies to specifically target cells. The success of using monoclonal antibodies for treatment is influenced by the level of target antigen found on cells.

Campath (anti CD52) is a treatment that is used to treat CLL after patients who have failed on other treatments. CD52 is a protein present on the surface of mature lymphocytes. Campath also known as Alemtuzumab targets CD52 antigen on cells. Campath is an expensive treatment and not always beneficial due to the CD52 level the cells are expressing.As yet there is not a technique established in the haematology department at Heart Of England Foundation Trust NHS hospital to assess the level of CD52 antigen on the cell.

CD52 expression can identify those patients who are likely to respond to Campath, and highlight those in which Campath will be ineffective.

Over the course of the project, 50 "normal" samples were analysed for CD 52 levels using flow cytometry to see what the average levels of CD52 are in a group of normal healthy individuals. 20 CLL recently diagnosed patients were also tested to see if there was a variation in results. Results from the two groups were compared and showed some conflicting results. It was found that samples left to incubate for longer than 15 minutes at 4°C lost their sensitivity when tested on the flow cytometer. It was also found that CLL patients expressed a lower CD52 level overall, however there is no clinical explanation for this. It is viable to see the patients that would find Campath benificial, these patients have a normal or elevated CD52 level.