Mice completely suppressed for the expression of immunoglobulin kappa light chain.

Abstract

Complete suppression of expression of immunoglobulin K light chain was achieved by injecting female mice from birth with a mixture of antisera against the jz heavy chain and K light chain (anti-AL and anti-K). Then their offspring were injected with anti-K from birth. This resulted in stable suppression as long as anti-K injections were continued. K light chain was not detectable either in serum or at the cellular level. The number of B cells in spleen and the concentration of immunoglobulin classes and subclasses in serum were normal. The normal levels were achieved by a compensating enhancement of A light chain expression. Analysis of the light chains of immunoglobulins secreted by spleen cells from suppressed mice after liposaccharide stimulation by two-dimensional gels showed A chain to have a limited heterogeneity. Primary responses to dinitrophenol, influenza strain A, and keyhole limpet hemocyanin were drastically affected, whereas secondary responses appeared to be quite normal, suggesting a surprisingly large potential repertoire.Two types of immunoglobulin light chains, K and X, are present in mammals and birds (1, 2). The reason for the parallel existence of two light chain types is unclear, especially because some species show a remarkable imbalance towards one or the other. In the horse, for example, X light chains are carried by about 95% of serum immunoglobulins (2), whereas in the mouse X light chains constitute only 2-5% of the serum light chain pool (2, 3). From sequence data of mouse myeloma proteins, it was concluded that this imbalance is a reflection of the number of germ-line genes for the variable (V) part of the particular light chain (4). Indeed, current estimates on the number of germ-line genes based on analysis at the DNA level are 100-200 V genes for K (VK) and two for X (VA) (5-7).The relative contribution of the two classes of light chain to the immune response can be evaluated in mice that ex-press only one type of light chain. The loss of X chain seems to have no drastic effects because SJL and BSVS mice, which display a lower expression-1/50th-of X chain than do other mouse strains (3,8,9), are not noticeably immune deficient.The effect of a loss of expression of K chain should be more drastic, given its major contribution (>90%) to the normal repertoire. The immune deficit due to loss of expression of K chain would be expected to depend upon the number of germ-line VA genes that the animal expresses. In the rabbit (normal level of K chain, 90-95%; refs. 2, 10), a strain exists that has lost the expression of the major K-type chain and whose immune system behaves quite normally (10). In this case it was shown that the V region of X chain is encoded by multiple (>20) germ-line genes (11), and a second K chain locus is expressed in higher quantities than normal (12). Because in mice only two VA genes exist, the complete loss of the expression of K chain should result in visible holes in the repertoire.

Pairing of VH gene families with the λ light chain: Evidence for a non‐stochastic association

“…We do not know. Certainly, the potential of the h f antibody is remarkably diverse [20] given the very limited diversity that can be generated by the murine h locus. Nevertheless, at least in the case of the 5558 gene family,VH + h l pairing do not constitute independent events.…”

“…The SJL mouse strain produces virtually no h+ antibody [4, 51 and yet is fully immunocompetent. Mice suppressed for the expression of x-bearing Ig are capable of producing hf antibody to a variety of antigens [20] and enumeration of antigenspecific, h+ Bcell colonies induced by LPS suggests an exceedingly diverse repertoire for h-bearing antibody…”

The Primary Antibody Repertoire of κ‐Deficient Mice is Characterized by Non‐Stochastic Vλ1 + VH Gene Family Pairings and a Higher Degree of Self‐Reactivity

“…These observations are in agreement with the studies by Sanchez et al [8], who showed in another k-deficient strain generated by a disrupted C k gene segment only, that 50-60% of l þ B cells in the periphery express the V l 1 gene. This is further supported by experiments with mice ᭧ 1998 Blackwell Science Ltd, Scandinavian Journal of Immunology, 48, 65-72 completely suppressed for k-light chain expression where 40-50% of splenic B-cell hybridomas and two-thirds of serum immunoglobulin expressed the l 1 -light chain [5]. Furthermore, a majority (42%) of B-cell clones from a population of l-enriched B lymphocytes from normal C57BL/6 mice were observed to express the Vl 1 gene [7].…”

“…Of the three available murine V l genes, V l 1 has been suggested to be predominantly expressed in 80% of Igl B cells [4]. In ksuppressed BALB/c mice, 30-40% of splenocytes expressed the l-light chain, with over 90% of these mice utilizing the l 1 subtype by 1 year of age [5]. Non-random V H gene expression and preferential V H þ V l associations have been observed in BALB/c mice immunized with anti-l-lipopolysaccharide (LPS) conjugates to activate l-secreting B-cell populations [11].…”

Evolution of the immunoglobulin heavy chain variable region (Igh-V) locus in the genusMus

“…The functional redundancy of the Igh-V locus has been established by the demonstration that multiple Vh genes, often belonging to different Vh gene families, are usually used in response to immunization with even a simple antigen [e. g., the antigens ARS (Margolies et al 1981), NP (Boersch-Supan et al 1985), HA (Clarke et al 1985), OX (Kaartinen et al 1986), TNP (Riley et al 1986), dextran (Alkokar et al 1987), and TGAL (Busto et al 1987); see also Riblet et al 1987]. Conversely, a particular Fh (or I0 gene may give rise to antibodies directed against distinct and apparently unrelated antigens (e. g., Weiss et al 1984, Schiffet al 1986, Naparstek et al 1986). Above a certain Fh gene pool size, additional functional diversity may not be gained with an increase in pool size; rather, beyond this point, the pool becomes progressively more redundant.…”