Synonyms in a broader sense
Agranulocytosis is a dramatic drop in the body’s own defence cells, the granulocytes, below 500 granulocytes per 1 microlitre of blood. The granulocytes are a subgroup of the white blood cells, the leukocytes. The white blood cells are the carriers of our immune system, the body’s own defences.
In addition to the granulocytes, there are also lymphocytes as a subgroup of the white blood cells, but they react more slowly to threats than the granulocytes, which is why the granulocytes are more important in the defence against bacteria or in sudden inflammatory reactions. A less severe form of granulocyte diminution is called granulocytopenia. The reason for agranulocytosis often lies in a drug-related cause.
The most important drugs that can trigger agranulocytosis as a side effect are some painkillers such as Metamizol®, non-steroidal anti-inflammatory drugs such as ASS (Aspirin), the anticoagulant Ticlopidine or antibiotics from the group of sulfonamides such as sulfamethoxazole. Neuroleptics or thyrostatic drugs are also considered possible triggers. These drugs can combine in the body with naturally occurring proteins in the blood (plasma proteins).
These compounds (complexes) of drug active ingredient and plasma protein are falsely recognised by the body as a threat and the body begins to produce so-called antibodies to mark the supposed enemy in the body for degradation. Ideally, these antibodies should only adhere to the surface of the complex perceived as a threat. Unfortunately, the surface of the body’s own innate defence cells, the granulocytes, resembles the surface of the drug-plasma protein complexes, which is why the antibodies formed also erroneously attach themselves to the surface of the granulocytes.
As soon as a cell is labelled with antibodies, the body begins to send out scavenger cells to fight them with every defence reaction and also completely breaks them down. Thus, due to a misinterpretation of the threat, the body begins to fight itself by attacking its own innate immune system. This form of agranulocytosis is called type 1 agranulocytosis and often occurs as a sudden (acute) clinical picture.
Another, less acute cause of agranulocytosis can be damage to the bone marrow, which hinders the actual formation of granulocytes. Examples are tumours of the bone marrow or toxic damage to the bone marrow after chemotherapy or various drugs. In these forms, in addition to agranulocytosis, there is also pancytopenia, i.e. a general reduction in the important cells that are formed in the bone marrow, including the red blood cells (erythrocytes) and blood platelets (thrombocytes). If pancytopenia is present, it is essential to investigate the cause in more detail, for example by taking a bone marrow sample.
Agranulocytosis is detected by an analysis of the composition of the blood, in the so-called differential blood count. To obtain the material for this, only a simple blood sample is required. If the number of granulocytes falls below 500 cells per microlitre of blood, this is called agranulocytosis. Furthermore, it must be asked and clarified which medications the patient is taking or has taken. In addition, bone marrow samples can also be groundbreaking for diagnostics in order to find out what the cause of agranulocytosis is.