Table of contents
Aims and Objectives
Aims and Objectives
The study aimed at investigating platelet count, MPV, PDW and P-LCR profiles as a diagnostic indices for thrombocytopenia and investigate sex differences.
Key words : Platelet count, MPV, PDW, P-LCR,
I use this opportunity to thank my beloved wife Mrs Ijeoma Anazali Okeke for her support throughout my program at Atlantic International University Hawaii. My gratitude goes to the entire academic department of Atlantic International University (AIU), our able academic dean Dr. Franklin Valcin, Dr. Jose Mercado, Lee Roobles and Dr. Gonzalez for their immense efforts in making AIU degree programs challenging, conducive, dynamic and reputability in all ramifications.
Many thanks to my academic advisors and teachers like Linda Collazo, Dr. Edgar Colon, Mrs Erica Smith and Dr. Igor Bondarenko for their guidance, advice, correction and prompt communication throughout my program at AIU. Please do not relent in teaching your students that which is profitable internationally , remember that all your tireless efforts are never forgotten.
Platelet counts and its associated indices of MPV, PDW and P-LCR were assayed in a total sample of 98 blood donors aged 19 to 55years here in Porto Novo. Among whom 47 were men(47.96%) and 51 were women (52.04%). The mean platelets count of 218.90 × 109/L were recorded among men samples while Platelet count of 247.8 × 109/L were recorded among women blood donors. The platelet count were slightly higher in women than men and this increase is not statistically significant (P=0.01). The indices of platelets, MPV, PDW and P-LCR were also variable among both men and women, again these are not statistically significant (P=0.01).
Conclusion: The present study showed that platelet count are gender dependent and platelet indices should be paid attention to when diagnosing thrombocytopenia. The routine hematologic autoanalyzers should incorporate reticulated platelet absolutely necessary for the accurate assessment of marrow response to thrombocytopenia.
Key words : Platelet count, MPV, PDW, P-LCR,
Corresponding Author: Peter Ubah Okeke
School of Sciences & Engineering
Atlantic International University
Platelets are anucleate blood cells that circulate at 150,000 to 450,000/mm3 with mean counts slightly higher in women than men Butkiewicz AM et al (2005). Platelets trigger primary hemostasis on exposure to physical and fluid stimulants that are associated with blood vessel injury. On a wright stained wedge preparation blood film, platelets are distributed through a monolayer at 7 to 21 per 100 × field and have an average diameter of 2.5µm, corresponding to a mean platelet volume(MPV) of 8 to 10 Fl in a direct preparation as determined by laboratory profiling instruments, Tsiara S et al(2003). The internal structure of platelets are complex and is scarcely visible using light microscopy.
Platelets arise from unique bone marrow cells called megakaryocytes. Megakaryocytes are among the largest cells in the body and are polyploidy. In healthy intact bone marrow tissue, megakaryocytes cluster in the extravascular compartment adjacent to the abluminal face of venous sinusoid endothelial cells Lichtman MA et al (1978). Other hematopoietic cells may cross the megakaryocyte cytoplasm to reach the sinusoid lumen, a faux phagocytosis called emperopolesis, Breton-Gorius J (1981). Megakaryocytes also are harvested from the lungs Pedersen NT(1974).
The hematopoietic stem cell named the colony forming unit granulocyte, erythrocyte, megakaryocyte, monocytes (CFU-GEMM) differentiates to the megakaryocyte lineage under the influence of hormone thrombopoietin(TPO) and a series of cytokines. There are three megakaryocyte lineage committed progenitor stages, defined by their culture colony characteristics. In order of differentiation, these are the burst forming unit (BFU-meg), colony forming unit(CFU-meg) and the light density CFU( LD-CFU-meg), Cramer EM &Vainchenker W (2006). All three resemble small lymphocytes and cannot be distinguished by wright stained light microscopy. The BFU-meg and CFU-meg are diploid and participate in normal mitosis, maintaining a pool of megakaryocyte progenitors. Their proliferative properties are reflected in their ability to form colonies of hundreds or scores (CFU) of progeny in culture. In contrast to the BFU-meg and CFU-meg, the LD-CFU-meg has little proliferative capacity and produces few cells but progresses to increased nuclear ploidy.
The LD-CFU-meg may be a transitional or promegakaryoblast stage in which polyploidy is established, but the morphology is indistinguishable from small lymphocytes. Megakaryocyte progenitors enter a second developmental compartment, terminal differentiation, as they lose their proliferative capacity.
In specialty laboratories, immunologic probes and flow cytometry are employed to identify megakaryocyte progenitors. Useful megakaryocyte and platelet specific immunologic markers are platelet factor 4 (PF4), von Willebrand Factor (vWF) and platelet glycoproteins Ib (CD42b) and IIb/IIIa (CD41), Cramer EM & Fontenay M(2006). Platelet peroxidase, localized in the endoplasmic reticulum of progenitors and megakaryoblasts also may be identified by cytochemical stain in transmission electron microscopy. Identical peroxidase activity is localized to the dense tubular system of mature platelets, George JN & Colman RW (2006).
Terminal Megakaryocyte Differentiation
Megakaryocyte progenitors leave the proliferative phase and enter terminal differentiation, where they are identified and staged using wright stained morphology in the bone marrow aspirate films or histologically by hematoxylin and eosin (H&E) stain in bone marrow biopsy sections. Past the LD-CFU-meg , there is no further mitosis, but three to four morphologically identifiable stages. Most hematologists use the terms MK I for megakaryoblast, MK II for promegakaryocyte and MK III for megakaryocyte, whereas others add a postmature MK IV stage characterized by a multilobed, highly condensed nucleus.
The MK I cannot be reliably distinguished from the myeloblast or pronormoblast on the basis of routine wright stained morphology of bone marrow aspirates with light microscopy. The microscopist can see plasma membrane blebs, blunt projections that resemble platelets or nuclear lobulation that reflects polyploidy; megakaryoblasts have a greater diameter than the other two blasts on average. Immunologic probes are often needed for definitive identification, the MK I may be identified using immunologic probes for the more differentiated membrane structures (CD42), GP IV (CD36), or mpl, which stands for the TPO receptor site. Immunological probes also may label cytoplasmic fibrinogen and vWF in α-granules.
Light microscopy aside, the MK I possesses most of the ultrastructure associated with the MK II and MK III stages and with platelets. The nucleus, although essentially round, reaches its fully ploidy at the MK I stage. The cytoplasm possesses α- granules and the demarcation system (DMS). The DMS, a series of membrane lined channels invades from the plasma membrane and grows over the course of terminal differentiation to subdivide the entire cytoplasm. MK III is the largest cell in the bone marrow easily detected with the 10 Χ objective. The nucleus is intensely lobulated and the chromatin is variably condensed. The cytoplasm is eosinophilic, granular, and platelet-like, owing to the through spread of the DMS and α-granules. The MK III is the stage from which platelet shedding or thrombopoiesis proceeds.
Megakaryocyte maturation is marked by a mysterious form of mitosis that lacks telophase and cytokinesis. This is refered to as endoreduplication or endomitosis, DNA synthesis proceeds to the production of 8N, 16N, or 32N ploidy with completely duplicated sets of chromosomes but no cell division. Some megakaryocytes reach 128N, although this level of ploidy may signal hematologic disease.
A single megakaryocyte may release 2000 to 4000 platelets. The search is ongoing for the molecular basis of endomitosis a cell cycle adaptation found in no other human cell. Just as mitosis ends at the progenitor stage, endomitosis is complete at MK I. The segmentation of the MK II and MK III nucleus probably reflects endomitosis in general, but the degree of duplication is not proportional to lobularity. Ploidy levels are measured easily using mepacrine a nucleic acid dye, in megakaryocyte flow cytometry, Choi ES et al (1995).