Thymic hypoplasia is a diseases of infancy in which the child is deprived of a thymus. Which of the following is expected to occur in an infant with thymic hypoplasia?

Options

A. Onset of respiratory distress and breathing difficulties
B. B-cells fail to mature and are not effective
C. Cell-mediated immunity is weak or non-existent
D. An increase in immunoglobulin (anti-body) levels

Answer

**Step-by-Step Solution:**

1. **Understanding Thymic Hypoplasia**: Thymic hypoplasia is a condition where the thymus gland is underdeveloped or absent. The thymus is crucial for the development of T-cells, which are essential for cell-mediated immunity.

2. **Impact on Immune System**: Since the thymus is responsible for the maturation of T-cells, its absence or underdevelopment leads to a significant impact on the immune system. Specifically, the production and maturation of T-cells are severely affected.

3. **Evaluating the Options**:
- **Option A**: Onset of respiratory distress and breathing difficulties. This is incorrect as it does not directly relate to the immune function affected by thymic hypoplasia.
- **Option B**: B cells fail to mature and are not effective. This is also incorrect because B-cells are primarily developed in the bone marrow, and their maturation is not directly dependent on the thymus.
- **Option C**: An increase in immunoglobulin (antibody) levels. This is false as well, since the lack of T-cells would lead to a compromised immune response, not an increase in antibodies.
- **Option D**: Cell-mediated immunity is weak or non-existent. This is the correct answer, as the absence of T-cells results in a significant reduction in cell-mediated immune responses.

4. **Conclusion**: The expected outcome in an infant with thymic hypoplasia is that cell-mediated immunity is weak or non-existent.

**Final Answer**: The correct answer is that cell-mediated immunity is weak or non-existent.

---