en Immunology Immunology Original Research: Basic Science in Medicine Original Research: Basic Science in Medicine The effect of natural killer (NK) cells and lymphokine activated killer ( LAK) cells was studied on a group of human melanoma cell lines. Peripheral blood from healthy volunteers was utilized as a fresh source of natural killer cells and rhI L-2 for producing LAK cells. The cytotoxicity of effector cells was quantified using a 4 hour SI determining the density of antigen expression on tumor cell surface. The majority of WM melanoma cell lines were relatively resistant to lysis by NK cells, but all showed high sensitivity to LAK cytotoxicity. The expression of MH C class I and I CAM-l on tumor cell lines varied, however using linear regression analysis between MH C class I and I CAM-l antigen expression, and UK/ pression of these antigens on the WM melanoma cell lines tested are independent of NK/ 155 160 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-335&slc_lang=en&sid=1 AR ANDALIB 20031947532846004440 20031947532846004440 Yes From Isfahan Medical School, Isfahan, I.R. Iran J LAWRY 20031947532846004441 20031947532846004441 No the Immunology Section of the Institute for Cancer Studies, Sheffield Medical School"Sheffield,. UK. R.c REES 20031947532846004442 20031947532846004442 No the Department of Life Sciences, the Nottingham Trent University, UK.