Thrombocyte concentrates are used frequently, especially for treating thrombocytopenia (too low platelet count) after chemotherapy and generally in the context of malignant diseases. In patients with a chronic need for platelets, apheresis concentrates are preferred to minimise the recipients' exposure. They are obtained from a single donor and are particularly suitable for patients already immunised - either by HLA-AK or platelet AK.
In general, platelet concentrates can be prepared in two ways.
On the one hand, by pooling 4-8 buffy coats or by single donation using platelet apheresis.
In terms of efficacy, they are equivalent. The disadvantage of pooled preparations results only from a higher donor exposure of the recipient and the risk of immunisation against HLA (human leukocyte antigens) or HPA (human platelet antigens).
Single-donor preparations are used when HLA-compatible products are indicated. HLA class I is expressed on the platelet. If a recipient has antibodies against these HLA characteristics due to a previous transfusion or pregnancy, the transfused platelets are "marked" with the recipient's antibodies and destroyed. The spleen and the liver are mainly involved in the destruction of platelets.
More detailed information about the supply of platelet concentrates can be found in the chapter " Treatment with TKS".
A platelet concentrate also has its own specifications: it must be leucocyte-depleted and contain no more than 10^6 leucocytes, and the minimum number of cells must be at least 2 x 10^11.
There is approximately 30 ml of residual plasma in a platelet concentrate. Otherwise, the platelets are suspended in a nutrient solution (PAS).
Pathogen-inactivated platelet concentrates can be stored at 22-26°C for 7 days under constant agitation (horizontal shakers). All platelet concentrates must be kept in horizontal shakers - not only the pathogen-inactivated ones.
For years now, more and more blood banks have been introducing pathogen inactivation to cover the so-called "new emerging pathogens". As far as I know, only the blood bank in Linz still uses platelet concentrates without pathogen inactivation.
Last update on 13.08.2023