Effects of Thymosin and Evidence of Monocyte Suppression of Both T‐ and B‐Cell Functions in Two Cases of ‘Common Variable Immunodeficiency’

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Abstract
We have studied two patients with common variable immunodeficiency (CVID) impaired cell‐mediated immunity. and high percentages of monocytes in their peripheral blood. Removal of monocytes from cultures of peripheral blood mononuclear cells from both patients increased the in vilro responses to phytohaemagglutinin (PHA) and concanavalin A (Con A) but not to purified protein derivative (PPD), as measured by [3H]thymidine uptake. Similarly, supernatants of monocyte cultures from both patients. unlike supernatants of normal monocytes, suppressed the in vitro responses to PHA and Con A but enhanced the response to PPD by cultured mononuclear cells from the patients and from normal donors. Addition of unfractionaicd mononuclear cells from both patients 10 normal mononuclear cells suppressed both pokeweed mitogen (PWM) stimulation and IgG production: this effect was abrogated by removal of monocytes from the patients’ mono‐nuclear cell populations. The effect of thymosin on both patients’ mononuclear cells was assayed in vitro. Thymosin was ineffective in vitro with cells from the first patient: for the other patient. [3H]thymidine uptake by mononuclear cells stimulated with PPD increased. whereas uptake by Con A‐stimulated cells decreased, as did the percentage of E rosette‐forming cells, providing further evidence of heterogeneity of the CVID syndrome. The effects of thymosin were also dependent on monocytes.