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Monoclonal antibody JC1: new reagent for studying cell proliferation
M C Garrido1, J L Cordell, M H Becker
1Nuffield Department of Pathology, John Radcliffe Hospital, Oxford.
Insights
A new antibody, JC1, identifies a nuclear antigen in proliferating cells, distinct from Ki67. JC1 shows promise as a proliferation marker, especially in squamous cell carcinomas where Ki67 is less effective.
Area of Science:
- Immunology
- Oncology
- Cell Biology
Background:
- Proliferating cells express specific nuclear antigens.
- Accurate identification of proliferating cells is crucial for cancer diagnosis and research.
- Existing markers like Ki67 have limitations in certain contexts.
Purpose of the Study:
- To characterize a novel mouse monoclonal antibody, JC1.
- To evaluate JC1's ability to recognize a nuclear antigen in proliferating cells.
- To compare JC1's performance with the established proliferation marker, Ki67.
Main Methods:
- Immunohistochemical staining of normal tissues and tumors using JC1 and Ki67 antibodies.
- Western blot analysis to determine the molecular weight of the antigen recognized by JC1.
- Testing of JC1 against recombinant Ki67 protein.
Main Results:
- JC1 recognizes a nuclear antigen with molecular weights of 212 and 123 kDa, distinct from Ki67 (395-345 kDa).
- JC1 shows reactivity in proliferating cells in various normal tissues and tumors, similar to Ki67.
- JC1 exhibits nuclear reactivity only and lacks cytoplasmic cross-reactivity seen with Ki67 in squamous cells. JC1 identified more cells in testis than Ki67.
Conclusions:
- JC1 is a novel antibody recognizing a nuclear antigen in proliferating cells.
- JC1 serves as a valuable adjunct to Ki67 for assessing cell proliferation.
- JC1 is particularly useful for proliferation assessment in squamous cell carcinomas where Ki67 determination is challenging.
Aim:
To characterise a newly developed mouse monoclonal antibody JC1 which recognises a nuclear antigen present in proliferating cells in normal tissues and neoplastic lesions, and which is absent in resting cells.
Methods:
The methodology was established using a representative range of frozen sections from normal tissues and from certain tumours which were immunostained with antibodies Ki67 and JC1. The molecular weight of the antigen recognised by JC1 was obtained by western blot analysis and this was compared with that of Ki67. IM-9 cell lysates containing Ki67 derived plasmids were also tested with JC1 antibody.
Results:
Biochemical investigation indicated that the antigen recognised by JC1 gives two molecular weight bands of 212 and 123 kilodaltons, which is distinct from the well characterised anti-proliferation monoclonal antibody Ki67 (395-345 kilodaltons). In addition recombinant Ki67 protein is not recognised by JC1. Immunohistological reactivity was seen in areas known to contain numerous proliferating cells such as lymphoid germinal centres, splenic white matter, cortical thymocytes and undifferentiated spermatogonia. In tumours many cells from adenocarcinomas, oat cell carcinomas, squamous cell carcinomas of lung, and seminomas were labelled by JC1 with a distribution and proportion similar to that seen with Ki67. In normal tissues the only apparent difference was in testis where JC1 stained a considerably greater number of cells than Ki67. In all cases studied the new antibody showed nuclear reactivity only. JC1 did not show any cytoplasmic crossreactivity with squamous cells as is frequently seen with Ki67.
Conclusion:
Antibody JC1, which recognises a nuclear antigen present in proliferating cells, should provide a useful adjunct to Ki67 as a marker of proliferation especially in those cases such as squamous cell carcinomas where a Ki67 index cannot be determined.
