Lambda antibodies identify surface immunoglobulin on both normal and malignant B-cells. Lambda staining typically appears in B-cell follicles within lymphoid tissues. Light chain analysis plays a vital role in diagnosing B-cell neoplasms:

• Most B-cell lymphomas express either kappa or lambda light chains exclusively.
• In contrast, reactive proliferations feature a mixed population of kappa- and lambda-positive cells.
• Monoclonality is suspected when:
• Kappa-to-lambda ratio ≥ 3:1
• Lambda-to-kappa ratio ≥ 2:1
• Over 75% of cells express a single light-chain type.

Additionally, immune complex-mediated glomerulonephritis (such as lupus nephritis) often shows positive
immunofluorescence for IgG, IgA, IgM, C3, C1, and either kappa or lambda light chains.