What is most likely to be concurrently observed in a cat with plasma cell gingivitis stomatitis?

In cases of plasma cell gingivitis stomatitis in cats, an increased serum gamma globulin concentration is commonly observed. This condition is associated with a dysregulation of the immune response, leading to a proliferation of plasma cells in the gingival tissues. The plasma cells are responsible for producing immunoglobulins, which contributes to the overall levels of gamma globulins in the serum. As the immune system becomes activated in response to the chronic inflammation present in the gingiva, the production of antibodies increases, resulting in elevated serum gamma globulin concentrations.

The other options, while they might be relevant in different contexts, are not characteristic findings associated with plasma cell gingivitis stomatitis. For example, firm raised lesions on the tongue are not a typical concurrent finding in this condition. Additionally, alveolar bone proliferation is more often associated with periodontal disease rather than specifically plasma cell gingivitis stomatitis, and herpesvirus isolation would pertain more to viral infections and not directly to the plasma cell component of gingivitis/stomatitis. Thus, the increase in serum gamma globulin serves as a key indicator of the underlying immune response associated with this condition in cats.