Ability of Rabbit IgG Fab' Fragment Specific for a Human Species Antigen to Block Reactivity of HL-A Antisera.
ARMY MEDICAL RESEARCH LAB FORT KNOX KY
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The relationship between a human species antigen and various HL-A antigens was investigated. IgG Fab fragment was prepared from a rabbit antihuman lymphocyte serum, anti-B.L. This antiserum was elicited by prolonged immunization of rabbits with purified lymphocytes from a single individual, B.L., and contained antibodies directed primarily toward a human species antigen or antigens. Lymphocytes from individuals positive for various HL-A antigens were preincubated with anti-B.L. IgG Fab fragment. As controls, lymphocytes were also preincubated with normal rabbit IgG Fab fragment and veronal buffered saline VBS. Lymphocytes were then incubated with various HL-A antisera and complement and stained with trypan blue. It was found that for all five HL-A antisera which could be tested, their cytotoxicity was blocked by preincubation with anti-B.L. IgG Fab fragment, but not normal rabbit IgG Fab fragment or VBS. This occurred whether or not the HL-A antigens involved were present on the original immunizing lymphocytes of individual B.L. It was concluded that anti-B.L. IgG Fab sterically inhibited the HL-A antisera, and that HL-A antigens were either contained in or located in close enough proximity to one or more human species antigens such that steric inhibition could occur. Author
- Medicine and Medical Research