Imbalance of CD4+ lymphocyte subsets in patients with mixed connective tissue disease.

CD4⁺ (helper/inducer) T lymphocyte subsets were studied in the peripheral blood from patients with mixed connective tissue disease (MCTD) by double-labelling immunofluorescence. The proportion of CD4⁺CD45RA⁺ cells was higher (P < 0.01) when compared with controls, whereas CD4⁺CD29⁺ cells were markedly diminished (P<0.001). CD4⁺CD29⁺ cells were lower than in patients with progressive systemic sclerosis who were studied in parallel. Upon stimulation with phytohaemagglutinin, CD4⁺ cells from MCTD patients showed a strong reactivity to acquire the CD29⁺ phenotype. Expression of high levels of CD29 and other adhesion molecules might lead to facilitated localization of CD4⁺ cells to inflamed tissue. It is suggested that an increased responsiveness of CD4⁺ cells to activation signals in vivo and accumulation of CD4⁺CD29⁺ cells at tissue sites could result in depletion of this cell subset in the peripheral blood of patients with MCTD. [ABSTRACT FROM AUTHOR]