what are immature polymorphoneuleocites?

Answer 1

You are referring to "PMN's", polymorphoneuclear leukocytes which are so named because the nucleus looks like a string of beads instead of a big circle in the middle of the cell... "poly"=many, "morph"=shape, -nucleus.

These are rapid response leukocytes (white blood cells) that respond to inflammation and immune activity in the body. If the immune system is an attacking army, these cells are the Marines... the first soldiers on the beach.

The reason that this comes up is that the lifespan of these PMN's is about 3 weeks (21 days). However, when they start going to war, they turn over a bit more rapidly. When that happens, the bone marrow starts kicking the newly formed cells out faster and earlier in development. One starts to see evidence of immature cells in the bloodstream.

This is not unlike the initiation of the draft in a time of war. The armed forces start taking in young people as fast as they can.

When PMN's are brand new out of the bone marrow, the nucleus - which is SUPPOSED to look like strings of beads, tends to look more like a piece of cooked bacon. The stringy parts between the beady parts haven't yet narrowed down to the very thin appearance that they have when they are older. When these parts which are supposed to be thin, are instead THICK, we call them "bands" or "band forms". This is a sign of immaturity.

When a blood specimen is analyzed under the microscope and the cells are counted (this is called a complete blood count or CBC - it is now typically done with an automatic machine unless we ask for a manual count) the relative number of white blood cells is counted as well as the percentage of band forms (immature PMN's).

If the white blood cell count is high, and the percentage of band forms is high, then it strongly indicates that the patient is actively responding to some sort of inflammatory problem. Typically this is a sign of infection.

If the white blood cell count is elevated, but the percentage of band forms is low, then sometimes it may point toward a non-inflammatory reason for an elevated white count.

However, all of this has to be compared against the overall evaluation of the patient. Without other clues, this alone is almost meaningless.

Answer 2

The previous answer posted couldn't be better if I tried to answer it myself. Immature PMN's are referred to as band forms and are the last stage of development before the nucleus becomes segmented, or as beads on a string. Other immature forms that are noted on a microscopic slide are metamylocytes, mylocytes, promylocytes and blasts. Each one is progressively more immature than the last. The progression of maturity for a PMN is from blast to promylocyte to mylocyte to metamylocyte to band to neutrophill, or PMN. These are all considered immature PMN's.