Deficiency of monoclonal antibody-defined NK Cells (HNK-1+) in primary immunodeficiency disorders

Oligodendrocyte myelin glycoprotein (OMgp): evolution, structure and function

The oligodendrocyte myelin glycoprotein (OMgp) is a glycosylphosphatidylinositol-anchored protein expressed by neurons and oligodendrocytes in the central nervous system (CNS). Although the precise function of OMgp is yet to be determined in vivo, recent in vitro studies suggested roles for this protein in both the developing and adult central nervous system. In vitro experiments demonstrated the participation of OMgp in growth cone collapse and inhibition of neurite outgrowth through its interaction with NgR, the receptor for Nogo. This function requires its leucine-rich repeat domain, a highly conserved region in OMgp during mammal evolution. OMgp leucine-rich repeat domain is also implicated in the inhibition of cell proliferation. Based on its developmental expression, localization and structure, OMgp may also be involved in the formation and maintenance of myelin sheaths. Cell proliferation, neuronal sprouting and myelination are crucial processes involved in brain development and regeneration after injury. Here, we review the information available on the structure and evolution of OMgp, summarize its tissue expression and discuss its putative role(s) during the development and in adult CNS.

Deficiency in circulating natural killer (NK) cell subsets in common variable immunodeficiency and X-linked agammaglobulinaemia

Absolute and relative NK cell numbers were determined in peripheral whole blood by flow cytometry in patients with common variable immunodeficiency (CVID) (n = 55) and X-linked agammaglobulinaemia (XLA) (n = 19) on regular immunoglobulin (IVIG) therapy. Absolute CD3-CD16+ NK cell numbers were significantly reduced in CVID patients (median 108/microl, range 23-815), compared with normal subjects (n = 60) (289/microl, range 56-640, P < 0.001). Total lymphocyte concentrations were significantly lower in CVID (median 1587/microl, range 523-7519) compared with normal subjects (median 2019/microl, range 1124-3149, P = 0.004), with the percentage of NK cells also being significantly decreased (median 7.5%, range 3.0-33. 0%, compared with 14.2%, range 2.6-30.8%, P < 0.001). In XLA, absolute NK cell numbers (median 140/microl, range 32-551, P < 0. 001) but not relative numbers were significantly reduced compared with normal controls. We excluded the possibility that IVIG interferes with in vitro binding of CD16 MoAbs. Further analysis of NK cell subsets showed a deficiency of both CD16+ and CD56+ cells in CVID, most marked in the CD3-CD8dim subpopulation, which may be due to increased homing of these cells to the gut. Serial studies on a small number of patients suggest that IVIG therapy has no short-term effect on NK cells, although we cannot exclude an effect with prolonged use. Although there are no obvious clinical effects of the NK depletion in CVID and XLA, this may be a factor in their predisposition to cancer.

Humoral immunity in nasal mucosa of patients with common variable immunodeficiency

Humoral immunodeficiency, as reflected by the low serum immunoglobulin (Ig) concentrations in adult patients with common variable immunodeficiency (CVID), was even more severely expressed at the B-cell level in their nasal mucosa. No Ig-producing cells could be detected by immunohistochemistry in 11 of 19 mucosal specimens. The epithelial distribution of secretory component (SC) was normal in all specimens, but a sign of SC-dependent IgM transport was seen in only three. Epithelial IgA was completely lacking. All patients had had recurrent lower respiratory tract infections and 16 had recurrent or chronic infections of the upper respiratory tract. A previous report indicated that the intestinal mucosa is a privileged site for maturation of B cells in patients with CVID; the present study shows that this does not hold true for the nasal mucosa. This difference in B-cell maturation may in part explain the preferential susceptibility to infections in the respiratory tract of patients with CVID.

A comparison of two fluorescence-activated cell sorters, the FACSIV (laser) and the FACSTm (mercury lamp), as research analyzers for the quantification of T and B cell subsets in human peripheral blood

T cell subset determinations were performed on 146 peripheral blood samples from healthy volunteers, and on 112 samples from immune deficient patients using two fluorescence-activated cell sorters (the FACSIV laser, and the FACSTm mercury lamp analyzer). The procedures necessary for the use and calibration of the FACSTm analyzer are discussed, and detailed. Using the FACSTm analyzer, counts were made of T and B cell subsets in 28 patients with multiple infections, 9 patients suffering from the acquired immune deficiency syndrome (AIDS) and 16 patients with a primary immunodeficiency disease. These results were compared with data obtained from 47 healthy volunteers, as control references. Results from the two instruments proved closely comparable, both qualitatively and quantitatively.