antigens autoimmunity bcells burkittlymphoma cd cdantigens celldifferentiation celltransformation cellular chemistry congresses differentiation dilution geneexpressionregulation genes genetics immunetolerance immunity immunoglobulingenes immunoglobulins immunologicalaspects immunologicaltolerance immunology indicatordilutiontechniques lymphocytes lymphoma methodology mhcclassii neoplasms neoplastic oncogenes physiology physiopathology plaqueassaytechnique research statisticalmethods t-lymphocytes tumors wh200w926b2000 wh525m486121992