Do you know what the abbreviations HCDM and HLDA mean?

The HCDM (Human Cell Differentiation Molecules) is an organization which defines the nomenclature of CD molecules and detects and records the reactivity of monoclonal antibodies against leukocyte surface molecules, on behalf of the IUIS (International Union of Immunological Societies, CD Nomenclature Sub-committee).

Antibody reactivity and assignment to CD nomenclature (Cluster of Differentiation, eg CD3, CD4, etc.) is determined experimentally in the so-called HLDA workshops (Human Leucocyte Differential Antigens). The first HLDA workshop in Paris in 1982 was co-organized by Cesar Milstein (Nobelist and "father" of monoclonal antibodies).

The individual HLDA workshops take place at the international level, and within their framework, monoclonal antibodies submitted by their developers, scientific groups or various commercial companies engaged in the production of antibodies are tested and compared.

Summary information on all antibody clones that have been validated in all workshops is archived on the HCDM website. The CD Maps project deals with the mapping of CD character expression on leukocyte subsets.


This information was kindly provided for you by Prof. T. Kalina, Ph. D., HCDM council member and CD Nomenclature Sub-committee member.


EXBIO Prague, together with several other world monoclonal antibody manufacturers, is one of the sponsors of the HCDM organization.


Engel P et al. CD Nomenclature 2015: Human Leukocyte Differentiation Antigen Workshops as a Driving Force in Immunology, J Immunol. 2015
Kalina T, Lundsten K, Engel P. Relevance of Antibody Validation for Flow Cytometry. Cytometry A. 2020
Kalina T, Fišer K, Pérez-Andrés M, et al. CD Maps—Dynamic Profiling of CD1–CD100 Surface Expression on Human Leukocyte and Lymphocyte Subsets. Front Immunol 2019



So how can you, our customers, find out if the clone you have chosen for your work has passed the HLDA workshop? In the case of EXBIO products easily - information about the workshop can be found on the EXBIO website directly on the product page:


If you have any further questions, please contact us by email on