The use of lymphocyte transformation and IgM estimation as diagnostic aids in leukaemoid reactions.

Twenty-two patients with lymphocytosis and sometimes accompanied by splenomegaly selected from our difficult diagnostic cases over the past two years are presented. The clinical and laboratory features pointed to one of the following: chronic lymphatic leukaemia without lymphadenopathy, lymphosarcoma or other lymphoreticular tumour, tropical splenomegaly syndrome with a lymphatic leukaemoid reaction. The precise diagnosis was usually made by haemotological laboratory tests - viz. (a) Lymphocytes transformation test (LTT) (b) Serum/Plasma IgM estimation. It was found that: (1) There was markedly raised IgM in the responders i.e. patients with Tropical Splenomegaly Syndrome (TSS) whose spleens regressed following treatment with antimalarials, contrasting the normal levels of IgM in the non-responders to antimalarial therapy. (2) The PHA - Lymphocytes Transformation in the TSS was normal while that of Chronic Lymphatic Leukaemia (CLL) was abnormally low. These combined tests (LTT & IgM) are recommended as investigations for leukaemoid reactions involving lymphocytes.