Question

A rapid decrease in the number of lymphocytes, monocytes and eosinophils best describes the mechanism of action of a. basiliximab b. mycophenolate mofetil c. tacrolimus d. corticosteroids e. immunoglobulin

Short answer

Answer: d. Corticosteroids

Step-by-step solution

Understand the question and provided options

In this multiple-choice question, we are given a MoA, which is a rapid decrease in the number of lymphocytes, monocytes, and eosinophils. Our task is to identify which of the provided options best fits the MoA description. Option a: Basiliximab Option b: Mycophenolate mofetil Option c: Tacrolimus Option d: Corticosteroids Option e: Immunoglobulins

Analyze the MoA of each option

We will now analyze the MoA of each option and compare it with the given MoA. a. Basiliximab: It is a chimeric monoclonal antibody that mainly binds to the IL-2 receptor on activated T cells, inhibiting their activation and proliferation. b. Mycophenolate mofetil: It is an immunosuppressive medication that inhibits inosine monophosphate dehydrogenase, impairing purine synthesis in lymphocytes. This leads to a selective suppression of T- and B-cell proliferation. c. Tacrolimus: It is an immunosuppressive drug that binds to FK506-binding protein (FKBP). The complex formed then binds to and inhibits calcineurin, preventing the dephosphorylation and subsequent activation of nuclear factor of activated T-cells (NF-AT). This prevents T-cell activation and interleukin-2 (IL-2) production. d. Corticosteroids: These are steroid hormones that mimic the natural hormone cortisol. They have anti-inflammatory and immunosuppressive effects by inhibiting the synthesis of various inflammatory mediators and inducing the production of anti-inflammatory proteins. They also cause a rapid decrease in the number of lymphocytes, monocytes, and eosinophils, which is the MoA described in the question. e. Immunoglobulins: These are proteins produced by the immune system in response to infections or other antigens. They serve various roles, including neutralizing pathogens, binding antigens, and promoting phagocytosis. They do not cause a rapid decrease in the number of lymphocytes, monocytes, and eosinophils.

Identify the correct answer

From the analysis, we can see that the best-described MoA in the question is that of corticosteroids which leads to a rapid decrease in the number of lymphocytes, monocytes, and eosinophils. Thus, the correct answer is: d. Corticosteroids

Key concepts

Lymphocytes

Lymphocytes are one of the primary cell types in the immune system, playing a critical role in the body's defense against pathogens. They circulate throughout the bloodstream and lymphatic system, and generally fall into two main types: B lymphocytes and T lymphocytes. B lymphocytes primarily produce antibodies, which neutralize foreign invaders. In contrast, T lymphocytes have various functions, such as killing infected host cells, assisting other immune cells, and regulating immune responses.

Lymphocyte counts can be affected by various medications and conditions. A decrease in their numbers can dampen the immune response, making the body less effective at fighting off infections. When we analyze the mechanism of action of different drugs, it is crucial to consider how they influence lymphocyte levels, as this has significant implications for a patient's immune system health.

Monocytes

Monocytes are a type of white blood cell that play a pivotal role in our immune system. They are noteworthy for their ability to differentiate into macrophages and dendritic cells in tissues, which are essential for phagocytosis and antigen presentation, respectively. The former engulfs and digests pathogens and cellular debris, while the latter presents antigens to T cells, playing an essential role in initiating an immune response.

Monocyte levels are indicative of the body's immunological status and inflammatory response. When a drug causes a rapid decrease in monocytes, it may lead to reduced inflammatory reactions and modulate immune responses, which can be desirable in conditions where the body's immune system is overactive, such as autoimmune diseases.

Eosinophils

Eosinophils are a lesser-known type of white blood cell, primarily associated with allergic reactions and parasitic infections. These cells contain granules loaded with potent chemicals that can destroy invading organisms, but which can also contribute to inflammation and tissue damage in the case of an allergic response.

The presence of eosinophils in blood and tissues can signify ongoing allergic or asthmatic conditions, but also infections with certain parasites. Medications interfering with eosinophil levels can help manage conditions like asthma, where reducing inflammation is a key therapeutic goal. Understanding the interaction of drugs with eosinophils can provide insight into their potential anti-inflammatory and immunosuppressive effects.

Corticosteroids

Corticosteroids hold a significant place in the pharmacological management of various inflammatory and autoimmune conditions. These synthetic drugs mimic the action of cortisol, a hormone that is naturally produced by the adrenal glands. Their anti-inflammatory and immunosuppressive effects come from their ability to modify the transcription of a wide range of cytokines and other proteins involved in inflammation.

Effect on White Blood Cells

One crucial aspect of corticosteroids' mode of action is their ability to lower the count of lymphocytes, monocytes, and eosinophils. This decrease is beneficial in conditions where the immune system is excessively active or in cases requiring a suppressed immune response, such as in transplant patients to avoid organ rejection. However, it's important to monitor these changes as they can leave individuals more susceptible to infections.

Immunosuppressants

Immunosuppressants are drugs that intentionally dampen the immune system's activity, reducing its ability to fight off infections but also helping to prevent the body from attacking itself in cases of autoimmune disorders or organ rejection after transplants. Various classes of immunosuppressants work through different mechanisms, but they commonly target T cells or other aspects of the immune response.

For instance, some interfere with the synthesis of DNA in proliferating cells, thereby selectively inhibiting the growth of immune cells. Others form complexes with proteins inside the cell to inhibit key signaling pathways involved in T-cell activation. A good understanding of these mechanisms can help clinicians to predict and manage the potential side effects that may come with immunosuppression, such as increased risk of infections or malignancies.