Question 3.1

College answer

Not available.

Discussion

"Left shift and toxic changes" is some anachronistic terminology still used to describe the morphological changes which occur in neutrophils in response to a variety of (usually infectious) stressors.

Causes of this picture:

• Sepsis
• Haemorrhage (due to adrenergic mobilisation of marrow neutrophils)
• Necrosis (of any sort, eg. ischaemia)
• Bone marrow infiltration (i.e. insufficient space for proper maturation)
• Anaemia (in an exaggerated haemopoietic reaction, the marrow releases a lot of immature cells, which include neutrophils)

Left shift is an increased proportion of immature granulocytes, predominantly neutrophils.

• At any given time, one should have no more than 3-5% of one's neutrophils represented by such band forms.
• If there is any more, that represents a "left shift", a change in the immature:mature ratio.
• According to Wikipedia, the term originates from some sort of "left-most button arrangement of early cell sorting machines", where the least mature cells (myeloblasts) were assigned to the left-most button of the manual counter.

"Toxic changes" are morphological changes seen in neutrophils, which occur as a part of widespread neutrophil activation (usually in response to systemic infection). To call "toxic changes" on a blood film, the laboratory scientist needs to find at least two out of three of the following morphological changes:

• Toxic granulation (an indicator of neutrophil immaturity)
• Toxic vacuolation (an indicator of phagocytosis)
• Döhle bodies (remnants of the rough endoplasmic reticulum)