Final answer:
Rheumatoid Factor is usually associated with the immunoglobulin IgM, which is involved in defense against parasitic infections and allergic responses.
Step-by-step explanation:
The Rheumatoid Factor is usually associated with the immunoglobulin IgM, which is a class of antibodies involved in the defense against parasitic infections and allergic responses. Rheumatoid Factor (RF) is an autoantibody, meaning it mistakenly targets the body's own tissues. In the case of rheumatoid arthritis, RF antibodies bind to IgG antibodies, forming immune complexes that contribute to the inflammation and joint damage associated with the disease.