Hematologic Manifestations of Human Immunodeficiency Virus

Introduction:

Acquired immunodeficiency syndrome (AIDS) is a life-threatening condition caused by HIV (human immunodeficiency virus). Around 38.5 million people worldwide are suffering from aids. It is considered the world's most serious public health problem and an epidemic (widespread condition of an infectious disease). AIDS causes damage to the body's immune system, disrupting the body's normal defense mechanism. This is associated with a spectrum of conditions caused by secondary infection and tissue changes. In this condition, normal bone marrow and blood cell functioning are also impaired, along with other tissues. That is why understanding the hematological manifestations is important for diagnosis purposes.

What Is HIV?

Human immunodeficiency viruses (HIV) are types of retrovirus. They enter the human body as single-stranded RNA ( Ribonucleic acid) viruses. After entering the target cells, they change into double-stranded DNA (deoxyribonucleic acid) with the help of the reverse transcriptase enzyme. There are two types of HIV viruses one is HIV-1 which is highly virulent and infectious, and another one is HIV-2, less infectious and mainly seen in West Africa.

• Transmission of HIV: The main mood of transmission of HIV is:

  • Through unprotected sexual contact. The virus can transmit through vaginal fluids, semen, and secretions of the genital organs.

  • During a blood transfusion, if the donor receives the blood of the infected person.

  • Needle prick, during a blood transfusion or surgical process, a used needle from an infected person can transmit the infection to the uninfected person.

  • It can transmit the child from the mother during pregnancy.

  • This infection is not transmitted through touch, kissing, or saliva.

• Pathophysiology of HIV: The envelope of the HIV viruses fused with the cell membranes of macrophages and CD4+T lymphocytes by adsorptions of glycoproteins. They can also infect dendritic cells (antigen-presenting cells) transmitted through the sexual route. After this, ribonucleic acid and various enzymes are injected into the cells. Here synthesis of complementary deoxyribonucleic acid (DNA). These infected CD4+ T cells are destroyed by CD8+ T cells. As a result, the number of CD4+ cells dropped dramatically. In the chronic phase, the drop in CD4+ T lymphocyte cells causes secondary infection. Infection also affects various cells like macrophages, monocytes, and microglia cells of the nervous system.

• Clinical Manifestations of HIV: The clinical symptoms include repeated fever, cough, cold, and rapid weight loss. On examination, several pathological entities can be observed. These are:

  • Multiple enlarged lymph nodes.

  • Fungal Infections: Candidiasis can be observed.

  • Viral Infections: Herpes simplex (a virus causing contagious sores around the mouth and body), herpes zoster (a virus causing rash) infection.

  • Bacterial Infections: Tuberculosis (a bacterial infection causing weight loss and dry cough), pneumonia infections (lung infection).

  • Parasite Infection: Toxoplasmosis infection.

  • Cancers Associated With AIDS Are:

    • Kaposi’s Sarcoma (a rare cancer of blood and lymph nodes).

    • Hodgkin lymphoma.

What Are the Blood Manifestations?

The general finding of the blood count of AIDS patients show:

• Anemia: This is the most common condition associated with HIV patients. The presence of few numbers of red blood cells in the blood characterizes this. This is also associated with low hemoglobin percentage. The cause of anemia is multifactorial; these are:

  • Antibody-Mediated Hemolysis: In this type of anemia, the destruction of red blood cells occurs due to an immune mechanism. Though this is mainly extravascular (outside the blood vessels), sometimes complement-mediated intravascular (inside the blood vessels) destruction of the red blood cells can also be seen.

  • Nutritional Deficiency: Nutritional deficiency of the affected person is also responsible for low levels of red blood cells and hemoglobin percentage.

  • HIV-Associated Nephropathy: HIV-associated nephropathy is associated with large kidneys, increased protein excretion through urine, and renal failure. As a result, the endogenous production of erythropoietin (a hormone responsible for stimulating red blood cells) is deceased. This causes a decreased number of red blood cells.

  • Bone Marrow Suppression: The proliferation of pro-inflammatory like IL-6 (interleukin 6), and TNF (tumor necrosis factor) due to the presence of HIV proteins (surface envelope glycoproteins) is responsible for bone marrow suppression. Also, drugs used in AIDS treatment, like Zidovudine, are responsible for increased red cell destruction.

• Neutropenia: A decreased number of neutrophils in the blood characterizes neutropenia. It is often associated with pancytopenia (decreased count of all blood cells) or decreased CD4+ T lymphocyte count. The causes of neutropenia are:

  • Most of the time, it is associated with the amount of viral load. The cytotoxicity of HIV is responsible for the impaired functioning of the hematopoietic stem cells (HSCs) or early myeloid progenitors, which are responsible for decreased neutrophil production.

  • Drugs like Amphotericin B and chemotherapeutic drugs such as Flucytosine, Foscarnet, and Ganciclovir are associated with bone marrow suppression and decreased production of neutrophils.

  • Along with this, the neutrophils in the blood are associated with reduced bactericidal capacity, defective degranulation process, impaired chemotaxis, defective surface adhesion mechanism, and impaired phagocytosis.

• Thrombocytopenia: The platelets count decreased in AIDS patients. The causative factors are:

  • Medications are the most common for thrombocytopenia. Cancer chemotherapeutic drugs like Flucytosine, Ganciclovir, Heparin, Quinidine/Quinine, Thiazides, and Valganciclovir are associated with it.

  • Cross-reactivity between HIV envelope glycoproteins 160/120 and platelet glycoprotein IIb/IIIa is responsible for the auto-immune destruction of platelets. Also, patients with advanced AIDS often have increased levels of C-reactive protein. This protein causes IgG-mediated platelet destruction.

• Coagulation Disorders In HIV: HIV-associated inflation and infection release inflammatory factors in the blood vessels. The local activation of tissue factors leads to the formation of microthrombi in the blood vessels. The risk factors are:

  • Antiviral toxicity and HIV replication.

  • Presence of other pathogens.

  • Host factors like smoking.

  • Venous damage caused by intravenous drugs.

What Are the Cancer Diseases?

AIDS patients often suffer from several blood cancers. These are:

• Hodgkin Lymphoma: This type of cancer originates from specific white blood cells. The presence of characteristic Reed-Sternberg cells (abnormal lymphocytes) is seen in these conditions. Enlarged lymph nodes, spleen, and liver are the main clinical features associated with this condition.

• Burkitt Lymphoma: This is a non-Hodgkin lymphoma associated with cytomegalovirus infection. This is associated with the infection of B-lymphocytes and usually affects children. This rare condition is associated with swollen lymph nodes and bellies and abnormal and prolonged abdominal pain.

Conclusion:

AIDS is a serious and life-threatening condition. Several organs are affected by the immunocompromised conditions associated with it. These conditions also affect the form and functionality of the blood cells. Proper diagnosis of the blood cell count and its functionality can be helpful for the diagnosis of HIV. Hematological pictures can also determine disease prognosis and the effect of the anti-retroviral therapy.