Question: Which of the following is first immunoglobulin that can be raised by early acute phase?
A IgA
B IgM
C IgG
D IgE
Answer: IgM
| Class of antibody | Description | When it is produced | Half-Life |
| IgM | The first class of antibody that is produced in response to an infection or antigen exposure. | Early acute phase | About 5 days |
| IgG | The most abundant antibody class in the bloodstream, providing long-term immunity. | Produced after IgM, primarily in the secondary response. | About 7 to 21 days |
| IgA | Found mainly in mucous membranes, providing localized protection in areas like the respiratory and digestive tracts. | Produced after IgM and IgG, primarily in the mucosal immune system. | Half-life varies but is generally shorter than IgG, typically a few days. |
| IgE | Primarily involved in allergic responses and parasitic infections. | Produced later in the immune response. | Very short half-life, measured in hours. |
| IgD | Found in small amounts on the surface of B cells and is not well-understood. | Produced in early B cell development. | Half-life is not well-defined but is likely relatively short. |