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Biomedical subjects

A Kaushik

Publications and source records attributed to A Kaushik.

At least 55 records · Page 3Linked to original sources
PubMed1991

Contribution of the VH11 gene family to mitogen-responsive B cell repertoire in C57BL/6 mice.

The contribution of VH11 gene family to the development of the primary B cell repertoire has been studied by analyzing 1.8 x 10(4) mitogen induced B lymphocyte colonies. The data demonstrate that VH11 family is predominantly expressed among neonatal splenic as well as adult peritoneal B cell colonies, both rich in Ly-1+ B cells. VH11 gene family expression among B splenocytes decreases during ontogeny and VH11 family pairs stochastically with different V kappa families among mitogen-activated neonatal B cell colonies, which are representative of an antigen unselected B cell repertoire. Thus, an increased VH11 expression among peritoneal and neonatal B cells points towards its biased expression among Ly-1+ B lymphocytes. The restricted V gene rearrangements and VH11-V kappa 9 pairing observed among anti-bromelain-treated mouse red blood cells autoantibodies are likely to be an outcome of both intrinsic gene recombination processes per se as well as selection by an autoantigen and/or local selective environmental factors.

Age Factors↗
PubMed1990

Identification of a new V kappa gene family that is highly expressed in hybridomas from an autoimmune mouse strain.

We have identified a new murine V kappa family that contains five to seven members, one member of which encodes the L chain V region of an anti-dsDNA antibody produced by a BALB/c hybridoma, C8.5. The cloned C8.5 V kappa gene exhibits highest homology with a human V kappa gene that was cloned from a nonproductive rearrangement but has never been seen in an expressed repertoire. Because this family was first identified in an autoantibody, we studied its expression in an autoimmune mouse strain. This V kappa family is expressed in 20% of hybridomas from NZB mice.

Amino Acid Sequence↗
PubMed1990

Ly1 and V-gene expression among hybridomas secreting natural autoantibody.

This report presents evidence that multispecific natural autoantibodies (NAAb) arise from both Ly-1+ and Ly-1- B lymphocyte subsets based upon detection of mRNA transcript of Ly1 gene by Northern blotting among hybridomas from several mouse strains. Newborn Xid mice also possess B cells transcribing the Ly-1 gene that secrete multispecific NAAbs. Different VH and VK gene families were expressed at random in both Ly-1+ and Ly-1- hybridoma clones secreting NAAbs. Certain VK gene families VK1, -8, -9, -10 and -19, were preferentially used by NAAbs. No particular VH:VK pairings were observed among NAAbs multispecifically reactive with DNA and cytoskeleton proteins. The NAAbs reactive with BrMRBC exhibited predominant pairing between VH11:VK9 gene families, although, for the first time, we noted the participation of VK1, -10 and -19 gene families in encoding this autoantibody specificity.

Animals↗
PubMed1990

Stochastic pairing of heavy-chain and kappa light-chain variable gene families occurs in polyclonally activated B cells.

Frequencies of 25 immunoglobulin heavy-chain and kappa light-chain variable (VH + V kappa) gene-family pairings expressed in splenic B-cell populations were determined by hybridization of VH- and V kappa-family-specific DNA probes to mitogen-induced B-cell colonies from C57BL/6 mice or hybridomas derived from BALB/c and NZB mice. Both analyses support the conclusion that VH and V kappa gene families pair without bias; as would be expected for random association, the frequencies of specific VH + V kappa pairs may be estimated by the product of the independent VH and V kappa frequencies. Based upon the frequencies at which 9 VH and 12 V kappa gene families are expressed, we calculated the expected usage for approximately 100 VH + V kappa family pairings in neonatal and adult C57BL/6 mice. Variability in the expression of such VH + V kappa pairings is considerable; pairs representing greater than 10% to less than 0.01% of the splenic B-cell population occur. This variability is most pronounced in the neonate, where 6 VH + V kappa family pairs account for nearly 40% of all mitogen-reactive B cells. As the neonate matures, the distribution of frequencies for VH + V kappa pairings becomes more nearly uniform. This process may underlie the patterned acquisition of humoral immune responsiveness.

Animals↗
PubMed1990

T and B cell status in bronchiolitis and bronchial asthma.

Immunologic status of 43 children, 13 with bronchiolitis and 30 with bronchial asthma was studied, and compared with 10 infants and 16 healthy children of respective control groups. Humoral immunity was assessed by absolute eosinophil count and B cell count (EAC rosette method) and cellular immunity by T cell count (E rosette method) and DNCB skin test. B cell subset of lymphocytes were raised in both the study groups but associated significant eosinophilia was seen only in bronchial asthma. The study demonstrated significantly lower mean T cell count and depressed DNCB reactivity in children of bronchial asthma. Children with bronchiolitis too had significantly lower mean T cell count. Thus both humoral and cellular immunity were altered in children with bronchial asthma and bronchiolitis.

Asthma↗
PubMed1989

Murine V kappa gene expression does not follow the VH paradigm.

V kappa gene family expression among LPS-reactive murine B lymphocytes, unlike that of VH gene families, is not proportional to genomic complexity, i.e., nonstoichiometric. Furthermore, no positional bias for the overexpression of J-proximal V kappa genes (V kappa 21) is observed among neonatal B lymphocytes. Yet, the V kappa 1 and V kappa 9 families located in the center of V kappa locus are preferentially used by neonatal B splenocytes. Thus, the mechanisms of V kappa gene rearrangement and expression appear to differ significantly from those controlling the VH locus.

Animals↗
PubMed1988

A member of a new VH gene family encodes antibromelinized mouse red blood cell autoantibodies.

A cDNA clone encoding the variable region of the heavy chain of a BALB/c antibromelinized mouse red blood cell (BrMRBC) monoclonal antibody has been characterized. The nucleic acid sequence indicates that the variable region of the heavy chain is likely encoded by variable-VCP12, diversity-DSP 2 (5, 7 or 8) and joining-JH1 germ-line genes. An identical combination of V genes was observed for six other CBA/J and NZB anti-BrMRBC hybridomas. The BALB/c VCP12 nucleotide sequence is less than 80% homologous to members of the 10 known VH families. Moreover, the genomic restriction fragments detected under moderate stringency conditions with the radiolabeled cDNA probe did not correspond to those obtained with probes of the most homologous VH families (7183 and X24). The results indicate that the VCP12 gene defines a new VH family which we propose to designate VH11. The observation of 1, 2 or 3 genomic restriction fragments at the most, with mice bearing the Igh-Vd or j, Igh-Va or b or Igh-Vc haplotypes, suggests the existence of a few VCP12-related genes.

Animals↗
PubMed1988

Comparative study of VH gene family usage by newborn xid and non-xid mice, newborn NZB and adult NZB mice, and by splenic and peritoneal cavity B cell compartments.

RNA from 170 different Ig-secreting hybridomas was hybridized with VH gene probes 7183, QUPC52, S107, J558, J606, 36-60, V31, X-24 and V-GAM 3.8, with the aim of comparing xid to non-xid mice, neonatal NZB to adult NZB, and the peritoneal cavity with the splenic compartments for VH gene family expression. Our results indicate that (a) defective F1 male xid mice express with high frequency 36-60 and J606 5' proximal VH families, when compared to non-xid F1 females of the same matings. (b) Neonatal NZB mice express 3' proximal 7183 and QUPC52 families with high frequency, when compared to adult mice and to the expected values derived from VH complexity. (c) Natural antibodies against cytoskeleton proteins, DNA, rabbit IgG and 2,4,6-trinitrophenyl did not appear to prefer a particular VH family. The only difference found is related to age; neonatal clones preferentially employ 7183 and QUPC52 while J558 predominates among adult clones. (d) All the 15 antibodies directed against bromelin-treated mouse red blood cells failed to hybridize with any of the nine VH probes employed. These results confirm previous findings indicating the highly homogeneous pattern of these latter antibodies, and suggest that they are encoded by a new VH family (VH11).

Animals↗
PubMed1988

Comparative analysis of natural antibody specificities among hybridomas originating from spleen and peritoneal cavity of adult NZB and BALB/c mice.

A preliminary experiment showed that the supernatants of in vitro cultured peritoneal cells (rich in Ly-1 B cell subset shown to secrete most IgM autoantibodies against bromelain-treated mouse red blood cells (BrMRBC) and DNA) from different mouse strains did not contain any significant antibody activity against DNA and cytoskeleton proteins, although the presence of anti-BrMRBC antibodies was clearly evident. Therefore, we investigated comparative natural antibody (NAb) specificities against an antigen panel (DNA, cytoskeleton proteins, IgG, bovine serum albumin (BSA), BrMRBC, trinitrophenyl (TNP), and trimethylammonium (TMA) haptens) among Ig-secreting hybridoma collections from the splenic (158) and peritoneal (230) immune compartments of autoimmune New Zealand black (NZB) and lipopolysaccharide (LPS)-stimulated BALB/c mice. The data showed: (i) isotypic restriction (mu and gamma 3 only), predominance of TMA ion-reactive (including BrMRBC) but negligible anti-DNA-reactive antibody specificities, and lack of simultaneous polyspecific widespread reactivity (i.e. at least four or more antigens) against DNA and cytoskeleton proteins in the peritoneal cavity; (ii) predominance of simultaneous widespread polyspecific reactivity against DNA and cytoskeleton proteins but negligible or no TMA hapten-reactive antibody specificities in the spleen. These observations reflect certain differences in the B cell repertoire of peritoneal cavity (rich in Ly-1 B cells) compared with spleen. The NAb against BrMRBC and those reactive with DNA and cytoskeleton proteins, which have been suggested to be secreted by the Ly-1 B cell subset, are distinguishable on the basis of the presence of separate recurrent idiotypes and preferential localization of B lymphocytes directed against these autoantigens.

Animals↗
PubMed1988

Do natural autoantibodies play an important role in the elimination of senescent or damaged red blood cells?

Natural autoantibodies (NAAbs) are an important constituent of circulating immunoglobins. Some demonstrate polyspecific reactivity and high idiotypic connectivity. For example, they are reactive with DNA and cytoskeleton protein; others exhibit restricted binding specificity. Among several hypotheses, we have explored the possibility that NAAbs constitute a physiologic system in the organism that participates in the elimination of dead tissues and cellular debris by opsonization and phagocytosis.

Autoantibodies↗
PubMed1987

Novel V genes encode virtually identical variable regions of six murine monoclonal anti-bromelain-treated red blood cell autoantibodies.

The variable (V) region sequences of six immunoglobulin M (IgM, kappa) monoclonal autoantibodies that recognize bromelinized isologous red blood cells, obtained by fusions of peritoneal cells from NZB or CBA/J nonimmunized mice with BALB/c myeloma cells, were determined by direct mRNA sequencing. The V regions of the light chains (VL) are almost identical with one another, as are the V regions of the heavy chains (VH), which, however, differ by six linked-base substitutions, depending on the strain of mice producing the autoantibodies. Such variations may reflect allelic differences. The VH segments determined have no obvious correspondence to any VH genes identified so far. They may belong to the small VH group 4, where 73% homology, at the most, can be calculated at the protein level for codons 1 to 94. Alternatively, the VH regions may be members of a new group of VH sequences not previously found. The V kappa regions appear closely homologous to members of the V kappa-9 subgroup of myeloma proteins of unknown antigen-binding specificity. The joining segments, J kappa and JH, used by the autoantibodies investigated, originate from the J kappa 2 and JH1 germ-line gene segments, respectively. The nine base-long diversity segments, D, derive from one member of the germ-line D gene SP2 family.

Animals↗
PubMed1987

Synovial chondromatosis presenting with peripheral nerve compression--a report of two cases.

We report two cases of synovial chondromatosis presenting with peripheral nerve compression syndromes involving respectively the median nerve at the wrist and the posterior interosseous nerve at the elbow. Only one previous instance of nerve compression due to this condition has been described, involving the ulnar nerve at the elbow. In one of our cases the disease process was at an early stage in its natural history and in the other at an advanced stage. The occurrence of nerve compression was related to the site rather than the stage of the disease. Full recovery followed local excision with decompression of the peripheral nerve involved.

Aged↗
PubMed1987

Age-related natural antibody specificities among hybridoma clones originating from NZB spleen.

In the studies presented here, age-related natural antibody specificities have been investigated in the autoimmune NZB mouse strain by cell fusion. The monoclonal immunoglobulins (MIg) secreted by productive hybridoma clones were examined for their antibody activities against a panel of antigens, including single- and double-stranded DNA, actin, tubulin, myosin, bromelain-treated mouse red blood cells (BrMRBC) and TNP-BSA, employing both direct and competitive enzyme immunoassays. The antibody specificities against this panel of antigens were strikingly frequent among hybridoma clones from neonatal NZB (49%) mice, compared to normal BALB/c neonates (8.8%) shown earlier. Among neonatal hybridomas with known antigen reactivities, 73% of the clones exhibited polyspecific binding. In contrast, the majority of hybridomas from 5- and 7-month-old NZB spleen reacted monospecifically (76%) with the antigens tested. Such a characteristic reactivity pattern reflects an age-related evolution of B-cell repertoire expression. Unlike normal BALB/c mice, a high frequency of monospecific TNP-hapten-reactive clones (75%) was noticed among hybridomas of known antigen reactivities from 5- and 7-month-old NZB-strain mice, an age when autoimmune haemolytic anaemia sets in. In conclusion, an elevated frequency of autoreactive clones among neonates (49%) and an aberrant expression of TNP-reactive clones in adults seem to be an outward signal of certain discrepancies at the level of B-cell repertoire expression in autoimmune NZB-strain mice.

Aging↗
PubMed1986

Autoantibodies against bromelainized mouse erythrocyte: strain distribution of serum idiotype expression and relative peritoneal cell activity.

Previously, we demonstrated that the naturally occurring mouse autoantibodies directed against bromelainized mouse red blood cells (BrMRBC) comprised a family of structurally related molecules bearing a common idiotypic determinant (CP) based on structural and idiotypic analysis of a series of anti-BrMRBC monoclonal autoantibodies derived from a fusion of peritoneal cells (PerC) with plasmacytomas. In the present studies, we have evaluated the quantitative expression of circulating CP idiotype related to autoantibodies against BrMRBC in relation to specific PerC anti-BrMRBC plaque-forming activity in an individual mouse of different strains. The data presented here show no direct relationship between serum CP idiotype expression and PerC anti-BrMRBC plaque-forming activity in an individual mouse of all strains tested. However, the circulating CP idiotype content is higher in strains, viz., CBA/J, NZB, C3H, BXSB, and Biozzi high responder (H) mice which exhibit a high perC autoantibody secretory activity against BrMRBC. The strains such as BALB/c, DBA2, SJL/J, CBA/N, and Biozzi low responder (L) express little or no circulating CP idiotype with a corresponding small or no PerC anti-BrMRBC activity. Furthermore, the PerC "auto"-immune phenomenon is markedly expressed in the normal CBA/J strain since these mice show a higher percentage ratio of CP idiotype over serum IgM (2.68%) as well as highest PerC anti-BrMRBC plaque-forming activity (11,319 +/- 18,029 plaques per million viable cells) compared to other normal and autoimmune strains tested. Nevertheless, the highest circulating serum CP idiotype (49.4 micrograms/ml) is observed in the autoimmune NZB mouse. The immunodeficient CBA/N mice fail to express detectable levels of CP idiotype in their serum. The experiments conducted in genetically selected outbred Biozzi (H and L) strain have revealed remarkable differences in serum CP idiotype expression as well as PerC anti-BrMRBC plaque-forming activity in these two lines. The expression of mouse PerC "auto"-immune phenomenon and quantitative circulation of CP idiotype in the serum seem to be related to regulatory mechanisms as for sheep erythrocytes and other natural antigens earlier demonstrated to be under polygenic regulation in Biozzi (H and L) mice.

Animals↗