Relationships between 2H4 (CD45RA) and UCHL1 (CD45RO) expression by normal blood CD4+CD8−, CD4−CD8+, CD4−CD8dim+, CD3+ CD4−CD8− and CD3−CD4−CD8− lymphocytes

SUMMARY We characterized and established relationships between the expression of membrane 2H4 (CD45R A) and UCHL1 (CD45RO) by enriched lymphocyte fractions prepared by selective immunomagnetic depletion of monoclonal antibody-defined populations. Cell fractions analysed in this study could be divided into two broad groups according to the presence (CD.3+VCD4+CD8−, CD3+CD4−CD8+ CD3+ CD4− CD8dim+ and CD3+CD4− CD8−) or absence (CD3−CD4−CD8dim+ and CD3− CD4− CD8−) of the CD3 antigen. Preliminary studies confirmed a reciprocal relationship for CD45RA and CD45RO expression by major lymphoid components and further showed that the level or intensity of membrane 2H4 staining (2H4+, 2H4int and 2H4−) could be directly related to UCHLI expression. As a reflection of their differential functions, the various CD3+ populations examined showed much greater heterogeneity in 2H4 and UCHLI expression. CD3+CD4+CD8 cells generally showed significant proportions of 2H4+, 2H4int and 2H4− components, whereas the CD3+CD4−CD8+ population was characterized by a predominance of 2H4+ cells. The results of this current investigation further suggested a higher proportion of dual-positive (2H4+ UCHL1+) cells and a much greater degree of inter-individual variation than previously suspected. In contrast to CD3* lymphocytes, natural killer (NK) associated CD3−CD4− CD8dim+ and CD3−CD4−CD8−populations were mostly 2H4+ with only minor 2H4int components and very low expression of UCHL1. An additional observation of note was that the proportions of 2H4+ and 2H4− cells comprising the CD4+ CD8− fraction in any given individual was highly correlated (P= 0·002) with the distributions of 2H4+ and 2H4− components within the CD4− CD8+ fraction. This suggests the possible existence of a common control mechanism for the acquisition of immunological memory by distinct lymphocyte populations and further indicates that individual variations in the distribution of 2H4/UCHLI lymphocyte subpopulations may be a direct consequence of immunological experience’ rather than age alone.