[Effects of FPIL6/IL2 on the differentiation and proliferation of lymphoid in the ML-IC assay]

To develop an in vitro assay that allows the culture and identification of a single human bone marrow progenitor closely related to hematopoietic stem cell, which is more primitive than LTC-IC, and to find an efficient culture conditions for NK-IC expansion.Fusion protein IL6/IL2 was reconstructed and expressed in E. coli DH5 alpha. ML-IC was determined by watching if the single cell can give rise to secondary progenitors with both LTC-IC and NK-IC characteristics. LTC-IC frequency was determined by the CFC clonogenic methylcellulose assay. NK-IC frequency was determined by phenotyping CD56 positive NK cells. The effect of FPIL6/IL2 on the expansion of NK-IC was examined by comparing the colony number of NK cells before and after the culture.After the initial 4-week expansion culture, we showed that (25.75 +/- 5.68)% of freshly sorted Lin-/34+/DRdim cells were able to generate functional NK-IC in one or more secondary FPIL6/IL2 cultures, whereas (6.81 +/- 1.97)% in the control. A total of 102 NK-IC cells were present when were cultured for 6-7 weeks in FPIL6/IL2 expansion medium, which was much higher than the 33 NK-IC cells in the control.ML-IC assay will prove useful to assess a very primitive hematopoietic cell with multilineage generative capacity. FPIL6/IL2 is capable of initiating and promoting NK-IC expansion greatly in ex vivo cultures in terms of net-conservation and net proliferation.