There are four isoforms of the CD1 proteins, designated CD1a, 1b, 1c and 1d.

Anti-CD1a clone 010 is effective in paraffin-embedded tissue: other antibodies require fresh frozen tissue2.

Immunohistochemical expression

CD1a, 1b and 1c are expressed by a range of antigen-presenting cells. CD1d is expressed by gastrointestinal epithelium and B lymphocytes.


 cutaneous lymphoid infiltrates

presence of dendritic cells strongly positive for CD1a






T-cell lymphomas



Diagnostic utility


1 S Pomplun. Immunohistochemical markers in the differentiation of thymic and pulmonary neoplasms. Abstract 158, Pathological Society of Great Britain and Ireland January 2001.

2 Leong A S-Y, Cooper K and Leong FJ W-M. Manual of diagnostic antibodies for immunohistology. 2nd edition, 2003

3 Schmuth M, Sidoroff A, Danner B, et al. Reduced number of CD1a+ cells in cutaneous B-cell lymphoma. Am J Clin Pathol 2001; 116:72-8


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