Background: There is evidence that patients with major depression (MD) also suffer an inflammatory immune reaction. However, the results remain ambiguous. This could be due to the psychiatrically heterogeneous patient samples investigated in many published studies. Since melancholic depression is psychopathologically and possibly etiologically different from non-melancholic MD, we focused on investigating immune parameters in these two subgroups.
Methods: 43 in-patients suffering from acute major depression were diagnosed, sub-classified according to DSM IV criteria, and compared to 43 matched healthy controls. Cell counts were determined by morphology, and acute phase proteins [c-reactive protein (CRP), alpha(2)-macroglobulin (A2M), haptoglobin (HP)] were measured by laser nephelometry. Cytokine production (IL-1beta) upon mitogen stimulation was measured by ELISA in a whole blood assay.
Results: Non-melancholic patients showed increased monocyte counts and A2M serum concentrations in the acute stage of disease and after 2 and 4 weeks of treatment. Melancholic patients demonstrated a decreased monocyte count upon admission and after 4 weeks of treatment. HP levels and IL-1beta production were unchanged in all studied subjects.
Limitations: Medication of the patients varied. The differentiation between melancholic and non-melancholic depression was performed clinically and was not performed using any standardized instrument.
Conclusion: Melancholic and non-melancholic patients show different immune patterns. This differentiation might clarify immunological findings in MD and point towards etiological factors that are involved in the development of various subtypes of MD.