Aphaeresis Thrombocytes, leukocytes removed

Characteristics:
An aphaeresis machine designed for this purpose is used to perform a donor thrombocyte aphaeresis. The thrombocytes are suspended in the plasma of the donor with this. The obtained thrombocytes may, alternatively, be suspended in a mixture of plasma and thrombocyte storage fluid. The leukocytes are either removed with the machine application or are, if necessary, still removed by passing the concentrate over a leukocyte-removing filter.

The volume of the product is 150 – 400 mL, with which there is an attempt to have the number of thrombocytes at a minimum of 250 x 109. The residual number of leukocytes is less than 1 x 106. The volume of the storage medium is adjusted to maintain a pH between 6.8 and 7.4 and to guarantee the presence of the ‘swirling effect’ (as an indicator of the morphology).

To the degree that there is more plasma present in the storage medium, it will contain more plasma proteins (although unstable coagulation factors are practically absent), the potassium is physiologic, the sodium is lightly elevated, and the glucose is (dependant upon the storage medium) lightly elevated to physiologic. There are practically no free calcium ions present and the citrate amount alternates between 15 and 25 mmol/L. The pH and glucose amount go down, and the lactate content increases, during the storage. The product contains leukocyte antigens and thrombocyte antigens from only one single donor.

Aphaeresis thrombocytes (single donor thrombocytes) originate from one donor. The donor is frequently selected on indication of identical or compatible HLA and/or HPA typing appropriate for a patient with HLA and/or HPLA antibodies (or for a patient with immune mediated refractoriness for random thrombocyte transfusions). Aphaeresis products from such selected donors can prevent the aphaeresis product from not fulfilling all of the demands of the currently applicable guidelines. If this is the case, then a decision must be made about use (magistral product), after consideration of availability and safety, and in consultation with the treating physician.

Indication
The product is usually prepared for the benefit of a patient that is refractory for thrombocyte transfusions as the result of antibodies against HLA antigens and/or HPA antigens. An HLA and/or HPA identical or compatible donor must be selected for such a patient.

NB. HLA typed products must be radiated in order to prevent GVHD (risk of a haploidentical donor).

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