Nokea
Which of the following pathogenic mechanisms are not typical for autoimmune reactions?
- A. Decreased functional activity of T-suppressors
- B. Loss of tolerance for T-helpers and B-lymphocytes
- C. Ag released by normally isolated tissues
- D. Formation of CD4+ cells
Correct Answer: D
Rationale: The correct answer is D, Formation of CD4+ cells. In autoimmune reactions, CD4+ cells are actually involved in the immune response. Here's the rationale:
1. CD4+ cells are helper T cells that play a crucial role in activating other immune cells in autoimmune reactions.
2. Decreased functional activity of T-suppressors (Choice A) is typical in autoimmune reactions as it leads to unchecked immune responses.
3. Loss of tolerance for T-helpers and B-lymphocytes (Choice B) is common in autoimmune reactions, where the immune system mistakenly attacks self-cells.
4. Ag released by normally isolated tissues (Choice C) is a typical mechanism in autoimmune reactions where self-antigens trigger immune responses.
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A child entering the school for the first time was given Mantoux test in order to determine if there was a need for revaccination. The reaction was negative. What is the meaning of this test result?
- A. No cell-mediated immunity to tuberculosis
- B. Availability of cell-mediated immunity to tuberculosis
- C. No antibodies to the tuberculosis bacteria
- D. No anti-toxic immunity to tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Availability of cell-mediated immunity to tuberculosis. A negative Mantoux test indicates the presence of an immune response to the TB bacteria, as the test measures the body's delayed hypersensitivity reaction to TB antigens. This means the child has been exposed to TB in the past or has been vaccinated, resulting in the development of cell-mediated immunity against TB.
Incorrect choices:
A: No cell-mediated immunity to tuberculosis - This is incorrect as a negative Mantoux test actually indicates the presence of cell-mediated immunity.
C: No antibodies to the tuberculosis bacteria - Mantoux test measures cell-mediated immunity, not antibody response.
D: No anti-toxic immunity to tuberculosis - Mantoux test does not assess anti-toxic immunity, it specifically measures cell-mediated immunity.
Clinical symptom, typical for erythema infectiosum is:
- A. Swelling of salivary glands
- B. Diarrhea
- C. Hepatitis
- D. Exanthematous rash
Correct Answer: D
Rationale: The correct answer is D: Exanthematous rash. Erythema infectiosum, also known as fifth disease, is characterized by a distinctive rash on the cheeks that looks like a "slapped cheek." This rash then spreads to the rest of the body, resulting in a lace-like rash (exanthem). Swelling of salivary glands (choice A) is not a typical symptom of erythema infectiosum. Diarrhea (choice B) and hepatitis (choice C) are also not associated with this condition. Therefore, the most characteristic clinical symptom of erythema infectiosum is the exanthematous rash.
Infectious mononucleosis most often occurs in:
- A. infants
- B. adolescents
- C. young adults
- D. the elderly
Correct Answer: B
Rationale: The correct answer is B: adolescents. Infectious mononucleosis is commonly caused by the Epstein-Barr virus, which is transmitted through saliva. Adolescents are more likely to engage in activities like kissing and sharing drinks, increasing the chances of virus transmission. Infants have maternal antibodies for protection, young adults may have developed immunity, and the elderly have had more exposure to the virus and may have built immunity over time.
A 40-year-old man developed skin redness and swelling in the neck area, where eventually a small abscess appeared. On section the focus is dense and yellow-green colored, in the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthoma cells, and macrophages detected. Specify the most correct etiological name of this pathological process:
- A. Syphilis
- B. Carbuncle
- C. Actinomycosis
- D. Leprosy
Correct Answer: C
Rationale: The correct answer is C: Actinomycosis. Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species, which form sulfur granules in purulent masses surrounded by dense fibrous tissue. In this case, the presence of fungal druses, plasma cells, xanthoma cells, and macrophages in the histological examination is characteristic of actinomycosis. The clinical presentation of skin redness, swelling, and abscess formation in the neck area also aligns with actinomycosis.
Choice A: Syphilis is caused by Treponema pallidum, presenting with a painless chancre at the site of infection, not skin redness and swelling in the neck area.
Choice B: Carbuncle is a bacterial skin infection involving a group of hair follicles, typically on the back of the neck, not characterized by fungal druses or sulfur granules.
Choice D: Leprosy
A wound smear revealed Gram-negative rods producing blue-green pigment. The bacteria had a fruity odor. What is the causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Proteus mirabilis
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known to produce a blue-green pigment called pyocyanin, which is characteristic of the organism. Additionally, it has a distinct fruity odor due to the production of certain volatile compounds. Escherichia coli (B) does not produce blue-green pigment or have a fruity odor. Klebsiella pneumoniae (C) and Proteus mirabilis (D) also do not exhibit these specific characteristics associated with Pseudomonas aeruginosa.