Question

Distinguish among the different types of blood cells and compare the functions of the various leukocytes.

As a complement to this discussion, conduct an online search for an article that has “breaking news” about new discoveries concerning blood. Briefly summarize the information you find in 100 words or fewer. Please don't forget to answer bold part. Thank you

Answer 1

Blood cells comprise of erythrocytes (red blood cells: RBC), leukocytes (white blood cells: WBC) and thrombocytes (platelets).

RBCs are enucleated biconcave discs, small, red in color and the most abundant. They help in oxygenation.

Platelets are the smallest (1/5th the size of RBC), but also round and enucleated. About 1 platelet is found for every 10-20 RBCs in a normal smear. They are cytoplasmic fragments of a large cell called megakaryocyte. They help in clotting.

WBCs are of 5 types, but are nucleated, living and involved in immunity. Those WBCs that contain cytoplasmic granules are called granulocytes.

It is very difficult to distinguish between neutrophils and eosinophils based on morphology because both are circular, have granulated cytoplasm and multi-lobed nucleus (2-5 lobes). So, they are collectively referred to as polymorphonuclear leukocytes.

1) Neutrophils: Most abundant and phagocytic.

2) Eosinophils: Limited phagocytosis, kills parasites.

3) Basophils: least abundant, functions in allergy and anaphylaxsis (bilobed nucleus with granulated cytoplasm).

Those without granules are agranulocytes.

4) Monocytes: Large, amoeboid shape, and phagocytic. Can differentiate into macrophages and dendritic cells, involved in antigen presentation in adaptive immunity

5) Lymphocytes: Made of natural killers cells, B- and T-cells, that aid in cell-mediated and humoral (antibody-mediated) adaptive immunity and infection memory and secondary immune responses.

"Breaking news" Fu, et al., 2018, Cell Stem Cell.

The blood is a liquid connective tissue and flows to almost every part of the body (except parts of the brain) and plays an important role in immune surveillance, as well as self vs. non-self discrimination during transplant rejection in graft vs. host disease (GvHD). Blood cells were thought to be produced only in the bone marrow from hematopoietic stem cells (HSCs) in adults. However, this study has shown that HSCs contributing to progenitors of multiple blood cell-type lineages are also produced by the human small interstine. When such interstine transplantation occurs, in case of patients suffering from diseases like Chron's disease in the small interstine, it resulted in blood chimerism. The donor's interstine found to produce blood cells including immune cells in the host. Additionally, it was found that the greater the number of blood and immune cells produced from the graft/donor interstine, the more tolerant was the host body to the graft and the chances of rejection were less.