Lymphocyte activation mutually with ECP level has been shown to correlate with acute exacerbations in asthma [82] . sECP is also reduced during immune therapy which is a regimen that suppresses lymphocyte activity [83] . Eosinophils have been shown to migrate to lymph nodes where they might interact with T-lymphocytes. Eosinophils up-regulate major histocompatibility complex class II [84] for antigen presentation, thereby possibly contributing to T-lymphocyte activation and the increased inflammatory response during allergic inflammation [85] . Eosinophils are also present in the lymphocyte rich organs, the thymus and spleen and lamina propria of the gastrointestinal (GI) tract [50] . Although no studies have shown any direct link between ECP release and lymphocyte function, ECP released during the inflammatory processes, co-localises with lymphocytes. In vitro ECP has been shown to influence the proliferation of T and B lymphocytes which indicate that the protein could regulate those cells in vivo ( Figure 6 ). This was shown when mononuclear cells (containing lymphocytes, 2 × 10 5 ) were incubated with or without phytohaemagglutinin (PHA) and low levels of ECP (1 nM -0.1 μM, 190 ng/mL-2 μg/mL) for 48 hr, resulting in 50-67 percent inhibition of proliferation of the lymphocyte fraction [86] . The cells were not killed by these low levels of ECP. B lymphocyte activity might also be influenced by ECP since low levels (0.5-1 ng/mL) inhibit immunoglobulin production by plasma cells [87] and by B lymphocyte cell lines [88] . This effect was inhibited by anti-ECP antibodies and ECP was not toxic to the cell lines as cell proliferation was not inhibited with these low concentrations. IL-6 could restore the immunoglobulin production by the plasma cells and IL-4 had the same influence on the B lymphocytes. Primary human A. Healthy Control B. Allergic rhinitis plasma cells and large activated B lymphocytes responded to ECP in a manner similar to that of the cell lines [87] . Thus, ECP might influence the immune system in that immature lymphocytes are inhibited in their proliferation by ECP while activated B lymphocytes respond by decreased immunoglobulin production (see Figure 6 ).