We have a paticulasr patient whose red cell are instantly agglutinated when suspended in Dia-Med diluent -2 . the cells behave normally when suspended in PBS Saline.

Has any other person come accross this problem .

Two things spring to mind - one simple and the other chasing zebras. Firstly, is your Dil2 at the same temperature as your PBS? If the PBS is at a slightly warmer temperature than your Dil2, it could just be that the red cells are already coated in a "cold reacting" antibody and that the change in temperature is sufficient to cause spontaneous agglutination. Secondly, it could be that your patient's red cells are low in sialic acid, and that something in the Dil2 is causing them to clump. Have you tried typing them for the M and N antigens?

I agree with Malcolm that it sounds as though your patient is aggregating because Diluent 2 is a LIS medium. Unless your Dil 2 has become contaminated?

Maybe I am wrong, but in my memory , low sialic acid cells will not agglutinated in lis.

^{I had the same problem with one of my patients also. I could wash cells with normal saline and all cells would be negative. Also ran anti-D as QC with washed cell and they reacted fine.  I then took same cells and resuspended with dil 2 and the cells became positive again. We had already called this patient as positive in the past but never transfused them. I ran screen by peg. It was negative.}

I found in the package insert for the MTS Diluent 2.  It lists Trimethoprim and Sulfamethoxazole as preservatives.  These are antibiotics and maybe some patients build antibodies to these drugs. Not sure but seems like this is what was going on in my case.